diff --git a/src/compile/dom/Block.ts b/src/compile/dom/Block.ts
index ca3984b5d729..f65fe79f36cb 100644
--- a/src/compile/dom/Block.ts
+++ b/src/compile/dom/Block.ts
@@ -241,7 +241,7 @@ export default class Block {
 			properties.addBlock(`m: @noop,`);
 		} else {
 			properties.addBlock(deindent`
-				${dev ? 'm: function mount' : 'm'}(#target, anchor) {
+				${dev ? 'm: function mount' : 'm'}(#target, anchor${this.compiler.options.nestedTransitions && ', introing'}) {
 					${this.builders.mount}
 				},
 			`);
@@ -281,10 +281,10 @@ export default class Block {
 				properties.addBlock(`i: @noop,`);
 			} else {
 				properties.addBlock(deindent`
-					${dev ? 'i: function intro' : 'i'}(#target, anchor) {
+					${dev ? 'i: function intro' : 'i'}(#target, anchor${this.compiler.options.nestedTransitions && ', introing'}) {
 						if (#current) return;
 						${this.builders.intro}
-						this.m(#target, anchor);
+						this.m(#target, anchor${this.compiler.options.nestedTransitions && ', introing'});
 					},
 				`);
 			}
@@ -293,7 +293,7 @@ export default class Block {
 				properties.addBlock(`o: @run,`);
 			} else {
 				properties.addBlock(deindent`
-					${dev ? 'o: function outro' : 'o'}(#outrocallback) {
+					${dev ? 'o: function outro' : 'o'}(#outrocallback${this.compiler.options.nestedTransitions && ', outroing'}) {
 						if (!#current) return;
 
 						${this.outros > 1 && `#outrocallback = @callAfter(#outrocallback, ${this.outros});`}
diff --git a/src/compile/dom/index.ts b/src/compile/dom/index.ts
index 3ced0254a24a..49012ab861c6 100644
--- a/src/compile/dom/index.ts
+++ b/src/compile/dom/index.ts
@@ -227,7 +227,7 @@ export default function dom(
 			this._fragment.c();
 			this._fragment.${block.hasIntroMethod ? 'i' : 'm'}(this.shadowRoot, null);
 
-			if (options.target) this._mount(options.target, options.anchor);
+			if (options.target) this._mount(options.target, options.anchor${compiler.options.nestedTransitions && ', 1'});
 		` : deindent`
 			if (options.target) {
 				${compiler.options.hydratable
@@ -239,7 +239,7 @@ export default function dom(
 				${options.dev &&
 				`if (options.hydrate) throw new Error("options.hydrate only works if the component was compiled with the \`hydratable: true\` option");`}
 				this._fragment.c();`}
-				this._mount(options.target, options.anchor);
+				this._mount(options.target, options.anchor${compiler.options.nestedTransitions && ', 1'});
 
 				${(compiler.hasComponents || target.hasComplexBindings || hasInitHooks || target.hasIntroTransitions) &&
 				`@flush(this);`}
diff --git a/src/compile/nodes/AwaitBlock.ts b/src/compile/nodes/AwaitBlock.ts
index 4897adcd59b7..7effc9c3ff1f 100644
--- a/src/compile/nodes/AwaitBlock.ts
+++ b/src/compile/nodes/AwaitBlock.ts
@@ -177,7 +177,7 @@ export default class AwaitBlock extends Node {
 				const ${countdown} = @callAfter(#outrocallback, 3);
 				for (let #i = 0; #i < 3; #i += 1) {
 					const block = ${info}.blocks[#i];
-					if (block) block.o(${countdown});
+					if (block) block.o(${countdown}, 1);
 					else ${countdown}();
 				}
 			`);
diff --git a/src/compile/nodes/Component.ts b/src/compile/nodes/Component.ts
index 526af029c8f2..de0f3f16b6e8 100644
--- a/src/compile/nodes/Component.ts
+++ b/src/compile/nodes/Component.ts
@@ -386,7 +386,7 @@ export default class Component extends Node {
 
 			block.builders.mount.addBlock(deindent`
 				if (${name}) {
-					${name}._mount(${parentNode || '#target'}, ${parentNode ? 'null' : 'anchor'});
+					${name}._mount(${parentNode || '#target'}, ${parentNode ? 'null' : 'anchor'}${compiler.options.nestedTransitions && ', introing'});
 					${this.ref && `#component.refs.${this.ref} = ${name};`}
 				}
 			`);
@@ -486,7 +486,7 @@ export default class Component extends Node {
 			}
 
 			block.builders.mount.addLine(
-				`${name}._mount(${parentNode || '#target'}, ${parentNode ? 'null' : 'anchor'});`
+				`${name}._mount(${parentNode || '#target'}, ${parentNode ? 'null' : 'anchor'}${compiler.options.nestedTransitions ? ', introing' : ''});`
 			);
 
 			if (updates.length) {
@@ -505,7 +505,7 @@ export default class Component extends Node {
 
 		if (this.compiler.options.nestedTransitions) {
 			block.builders.outro.addLine(
-				`if (${name}) ${name}._fragment.o(#outrocallback);`
+				`if (${name}) ${name}._fragment.o(#outrocallback, outroing);`
 			);
 		}
 	}
diff --git a/src/compile/nodes/EachBlock.ts b/src/compile/nodes/EachBlock.ts
index 2a62249c6326..c941638d233c 100644
--- a/src/compile/nodes/EachBlock.ts
+++ b/src/compile/nodes/EachBlock.ts
@@ -203,7 +203,7 @@ export default class EachBlock extends Node {
 
 			block.builders.mount.addBlock(deindent`
 				if (${each_block_else}) {
-					${each_block_else}.${mountOrIntro}(${parentNode || '#target'}, null);
+					${each_block_else}.${mountOrIntro}(${parentNode || '#target'}, null${this.compiler.options.nestedTransitions && ', 1'});
 				}
 			`);
 
@@ -310,12 +310,11 @@ export default class EachBlock extends Node {
 		}
 
 		block.builders.mount.addBlock(deindent`
-			for (#i = 0; #i < ${blocks}.length; #i += 1) ${blocks}[#i].${mountOrIntro}(${initialMountNode}, ${anchorNode});
+			for (#i = 0; #i < ${blocks}.length; #i += 1) ${blocks}[#i].${mountOrIntro}(${initialMountNode}, ${anchorNode}${this.compiler.options.nestedTransitions ? ', 1' : ''});
 		`);
 
 		const dynamic = this.block.hasUpdateMethod;
 
-		const rects = block.getUniqueName('rects');
 		const destroy = this.block.hasAnimation
 			? `@fixAndOutroAndDestroyBlock`
 			: this.block.hasOutros
@@ -335,7 +334,7 @@ export default class EachBlock extends Node {
 			const countdown = block.getUniqueName('countdown');
 			block.builders.outro.addBlock(deindent`
 				const ${countdown} = @callAfter(#outrocallback, ${blocks}.length);
-				for (#i = 0; #i < ${blocks}.length; #i += 1) ${blocks}[#i].o(${countdown});
+				for (#i = 0; #i < ${blocks}.length; #i += 1) ${blocks}[#i].o(${countdown}, 1);
 			`);
 		}
 
@@ -385,7 +384,7 @@ export default class EachBlock extends Node {
 
 		block.builders.mount.addBlock(deindent`
 			for (var #i = 0; #i < ${iterations}.length; #i += 1) {
-				${iterations}[#i].${mountOrIntro}(${initialMountNode}, ${anchorNode});
+				${iterations}[#i].${mountOrIntro}(${initialMountNode}, ${anchorNode}${this.compiler.options.nestedTransitions && ', 1'});
 			}
 		`);
 
@@ -397,8 +396,9 @@ export default class EachBlock extends Node {
 
 		const outroBlock = this.block.hasOutros && block.getUniqueName('outroBlock')
 		if (outroBlock) {
+			const outroArg = this.compiler.options.nestedTransitions ? ', outroing' : '';
 			block.builders.init.addBlock(deindent`
-				function ${outroBlock}(i, detach, fn) {
+				function ${outroBlock}(i, detach, fn${outroArg}) {
 					if (${iterations}[i]) {
 						${iterations}[i].o(() => {
 							if (detach) {
@@ -406,7 +406,7 @@ export default class EachBlock extends Node {
 								${iterations}[i] = null;
 							}
 							if (fn) fn();
-						});
+						}${outroArg});
 					}
 				}
 			`);
@@ -451,7 +451,7 @@ export default class EachBlock extends Node {
 			if (this.block.hasOutros) {
 				destroy = deindent`
 					@groupOutros();
-					for (; #i < ${iterations}.length; #i += 1) ${outroBlock}(#i, 1);
+					for (; #i < ${iterations}.length; #i += 1) ${outroBlock}(#i, 1${this.compiler.options.nestedTransitions && ', null, 1'});
 				`;
 			} else {
 				destroy = deindent`
@@ -482,7 +482,7 @@ export default class EachBlock extends Node {
 			block.builders.outro.addBlock(deindent`
 				${iterations} = ${iterations}.filter(Boolean);
 				const ${countdown} = @callAfter(#outrocallback, ${iterations}.length);
-				for (let #i = 0; #i < ${iterations}.length; #i += 1) ${outroBlock}(#i, 0, ${countdown});`
+				for (let #i = 0; #i < ${iterations}.length; #i += 1) ${outroBlock}(#i, 0, ${countdown}${this.compiler.options.nestedTransitions && ', 1'});`
 			);
 		}
 
diff --git a/src/compile/nodes/Element.ts b/src/compile/nodes/Element.ts
index a3040b81c241..86e72110eb8e 100644
--- a/src/compile/nodes/Element.ts
+++ b/src/compile/nodes/Element.ts
@@ -745,8 +745,11 @@ export default class Element extends Node {
 		const { intro, outro } = this;
 
 		if (!intro && !outro) return;
+		const nested = this.compiler.options.nestedTransitions;
 
 		if (intro === outro) {
+			const [transitionName, ...pipes] = intro.name.split('|');
+			const local = ~pipes.indexOf('local') && 1;
 			const name = block.getUniqueName(`${this.var}_transition`);
 			const snippet = intro.expression
 				? intro.expression.snippet
@@ -754,23 +757,23 @@ export default class Element extends Node {
 
 			block.addVariable(name);
 
-			const fn = `%transitions-${intro.name}`;
+			const fn = `%transitions-${transitionName}`;
 
 			block.builders.intro.addConditional(`#component.root._intro`, deindent`
 				if (${name}) ${name}.invalidate();
 
 				#component.root._aftercreate.push(() => {
-					if (!${name}) ${name} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, true);
-					${name}.run(1);
+					if (!${name}) ${name} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, 1${nested && `, ${local}`});
+					${name}.run(1${nested && ', null, introing'});
 				});
 			`);
 
 			block.builders.outro.addBlock(deindent`
-				if (!${name}) ${name} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, false);
+				if (!${name}) ${name} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, 0${nested && `, ${local}`});
 				${name}.run(0, () => {
 					#outrocallback();
 					${name} = null;
-				});
+				}${nested && ', outroing'});
 			`);
 
 			block.builders.destroy.addConditional('detach', `if (${name}) ${name}.abort();`);
@@ -780,11 +783,13 @@ export default class Element extends Node {
 
 			if (intro) {
 				block.addVariable(introName);
+				const [transitionName, ...pipes] = intro.name.split('|');
+				const local = ~pipes.indexOf('local') && 1;
 				const snippet = intro.expression
 					? intro.expression.snippet
 					: '{}';
 
-				const fn = `%transitions-${intro.name}`; // TODO add built-in transitions?
+				const fn = `%transitions-${transitionName}`; // TODO add built-in transitions?
 
 				if (outro) {
 					block.builders.intro.addBlock(deindent`
@@ -795,19 +800,21 @@ export default class Element extends Node {
 
 				block.builders.intro.addConditional(`#component.root._intro`, deindent`
 					#component.root._aftercreate.push(() => {
-						${introName} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, true);
-						${introName}.run(1);
+						${introName} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, 1${nested && `, ${local}`});
+						${introName}.run(1${nested && ', null, introing'});
 					});
 				`);
 			}
 
 			if (outro) {
 				block.addVariable(outroName);
+				const [transitionName, ...pipes] = outro.name.split('|');
+				const local = ~pipes.indexOf('local') && 1;
 				const snippet = outro.expression
 					? outro.expression.snippet
 					: '{}';
 
-				const fn = `%transitions-${outro.name}`;
+				const fn = `%transitions-${transitionName}`;
 
 				block.builders.intro.addBlock(deindent`
 					if (${outroName}) ${outroName}.abort(1);
@@ -816,8 +823,8 @@ export default class Element extends Node {
 				// TODO hide elements that have outro'd (unless they belong to a still-outroing
 				// group) prior to their removal from the DOM
 				block.builders.outro.addBlock(deindent`
-					${outroName} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, false);
-					${outroName}.run(0, #outrocallback);
+					${outroName} = @wrapTransition(#component, ${this.var}, ${fn}, ${snippet}, 0${nested && `, ${local}`});
+					${outroName}.run(0, #outrocallback${nested && ', outroing'});
 				`);
 
 				block.builders.destroy.addConditional('detach', `if (${outroName}) ${outroName}.abort();`);
diff --git a/src/compile/nodes/IfBlock.ts b/src/compile/nodes/IfBlock.ts
index eef654b90bbb..f1255256a933 100644
--- a/src/compile/nodes/IfBlock.ts
+++ b/src/compile/nodes/IfBlock.ts
@@ -140,7 +140,7 @@ export default class IfBlock extends Node {
 
 				if (this.compiler.options.nestedTransitions) {
 					block.builders.outro.addBlock(deindent`
-						if (${name}) ${name}.o(#outrocallback);
+						if (${name}) ${name}.o(#outrocallback, 1);
 						else #outrocallback();
 					`);
 				}
@@ -152,7 +152,7 @@ export default class IfBlock extends Node {
 
 			if (hasOutros && this.compiler.options.nestedTransitions) {
 				block.builders.outro.addBlock(deindent`
-					if (${name}) ${name}.o(#outrocallback);
+					if (${name}) ${name}.o(#outrocallback, 1);
 					else #outrocallback();
 				`);
 			}
@@ -206,7 +206,7 @@ export default class IfBlock extends Node {
 		const initialMountNode = parentNode || '#target';
 		const anchorNode = parentNode ? 'null' : 'anchor';
 		block.builders.mount.addLine(
-			`${if_name}${name}.${mountOrIntro}(${initialMountNode}, ${anchorNode});`
+			`${if_name}${name}.${mountOrIntro}(${initialMountNode}, ${anchorNode}${this.compiler.options.nestedTransitions ? ', 1' : ''});`
 		);
 
 		const updateMountNode = this.getUpdateMountNode(anchor);
@@ -292,7 +292,7 @@ export default class IfBlock extends Node {
 		const anchorNode = parentNode ? 'null' : 'anchor';
 
 		block.builders.mount.addLine(
-			`${if_current_block_type_index}${if_blocks}[${current_block_type_index}].${mountOrIntro}(${initialMountNode}, ${anchorNode});`
+			`${if_current_block_type_index}${if_blocks}[${current_block_type_index}].${mountOrIntro}(${initialMountNode}, ${anchorNode}${this.compiler.options.nestedTransitions ? ', 1' : ''});`
 		);
 
 		const updateMountNode = this.getUpdateMountNode(anchor);
@@ -374,7 +374,7 @@ export default class IfBlock extends Node {
 		const anchorNode = parentNode ? 'null' : 'anchor';
 
 		block.builders.mount.addLine(
-			`if (${name}) ${name}.${mountOrIntro}(${initialMountNode}, ${anchorNode});`
+			`if (${name}) ${name}.${mountOrIntro}(${initialMountNode}, ${anchorNode}${this.compiler.options.nestedTransitions ? ', 1' : ''});`
 		);
 
 		const updateMountNode = this.getUpdateMountNode(anchor);
diff --git a/src/shared/index.js b/src/shared/index.js
index 066942f1a627..41cf86071966 100644
--- a/src/shared/index.js
+++ b/src/shared/index.js
@@ -147,8 +147,8 @@ export function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-export function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+export function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 export var PENDING = {};
diff --git a/src/shared/transitions.js b/src/shared/transitions.js
index 8dfa50b8ffba..0020f2b1ccb9 100644
--- a/src/shared/transitions.js
+++ b/src/shared/transitions.js
@@ -26,7 +26,7 @@ export function hash(str) {
 	return hash >>> 0;
 }
 
-export function wrapTransition(component, node, fn, params, intro) {
+export function wrapTransition(component, node, fn, params, intro, local) {
 	let obj = fn.call(component, node, params);
 	let duration;
 	let ease;
@@ -40,28 +40,34 @@ export function wrapTransition(component, node, fn, params, intro) {
 		program: null,
 		pending: null,
 
-		run(b, callback) {
+		run(b, callback, introOutro) {
 			if (typeof obj === 'function') {
 				transitionManager.wait().then(() => {
 					obj = obj();
-					this._run(b, callback);
+					this._run(b, callback, introOutro);
 				});
 			} else {
-				this._run(b, callback);
+				this._run(b, callback, introOutro);
 			}
 		},
 
-		_run(b, callback) {
+		_run(b, callback, introOutro) {
 			duration = obj.duration || 300;
 			ease = obj.easing || linear;
 
+			if (introOutro && local) {
+				this.t = b;
+				if (callback) callback();
+				return;
+			}
+
 			const program = {
 				start: window.performance.now() + (obj.delay || 0),
 				b,
 				callback: callback || noop
 			};
 
-			if (intro && !initialised) {
+			if (b && !initialised) {
 				if (obj.css && obj.delay) {
 					cssText = node.style.cssText;
 					node.style.cssText += obj.css(0, 1);
diff --git a/src/validate/html/validateElement.ts b/src/validate/html/validateElement.ts
index 3d2d96f380b5..6264c9996304 100644
--- a/src/validate/html/validateElement.ts
+++ b/src/validate/html/validateElement.ts
@@ -85,11 +85,11 @@ export default function validateElement(
 		if (attribute.type === 'Ref') {
 			if (!isValidIdentifier(attribute.name)) {
 				const suggestion = attribute.name.replace(/[^_$a-z0-9]/ig, '_').replace(/^\d/, '_$&');
-				
+
 				validator.error(attribute, {
 					code: `invalid-reference-name`,
 					message: `Reference name '${attribute.name}' is invalid — must be a valid identifier such as ${suggestion}`
-				});	
+				});
 			} else {
 				if (!refs.has(attribute.name)) refs.set(attribute.name, []);
 				refs.get(attribute.name).push(node);
@@ -213,7 +213,7 @@ export default function validateElement(
 			validator.used.events.add(attribute.name);
 			validateEventHandler(validator, attribute, refCallees);
 		} else if (attribute.type === 'Transition') {
-			validator.used.transitions.add(attribute.name);
+			validator.used.transitions.add(attribute.name.split('|')[0]);
 
 			const bidi = attribute.intro && attribute.outro;
 
@@ -249,7 +249,7 @@ export default function validateElement(
 			if (attribute.outro) hasOutro = true;
 			if (bidi) hasTransition = true;
 
-			if (!validator.transitions.has(attribute.name)) {
+			if (!validator.transitions.has(attribute.name.split('|')[0])) {
 				validator.error(attribute, {
 					code: `missing-transition`,
 					message: `Missing transition '${attribute.name}'`
diff --git a/test/cli/samples/amd/expected/Main.js b/test/cli/samples/amd/expected/Main.js
index 5f236d668fe5..3832147408fd 100644
--- a/test/cli/samples/amd/expected/Main.js
+++ b/test/cli/samples/amd/expected/Main.js
@@ -165,8 +165,8 @@ define("test", function() { "use strict";
 		assign(this._staged, newState);
 	}
 
-	function _mount(target, anchor) {
-		this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+	function _mount(target, anchor, introing) {
+		this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 	}
 
 	function _differs(a, b) {
diff --git a/test/cli/samples/basic/expected/Main.js b/test/cli/samples/basic/expected/Main.js
index ba35a0c1e911..e3d4768f656c 100644
--- a/test/cli/samples/basic/expected/Main.js
+++ b/test/cli/samples/basic/expected/Main.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/custom-element/expected/Main.js b/test/cli/samples/custom-element/expected/Main.js
index 40865a2c81cd..fcd458a73244 100644
--- a/test/cli/samples/custom-element/expected/Main.js
+++ b/test/cli/samples/custom-element/expected/Main.js
@@ -186,8 +186,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dev/expected/Main.js b/test/cli/samples/dev/expected/Main.js
index bf46dffdd00c..d558fc8aac3f 100644
--- a/test/cli/samples/dev/expected/Main.js
+++ b/test/cli/samples/dev/expected/Main.js
@@ -191,8 +191,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir-sourcemap/expected/Main.js b/test/cli/samples/dir-sourcemap/expected/Main.js
index 0c0fab609439..4c6e1441f0e5 100644
--- a/test/cli/samples/dir-sourcemap/expected/Main.js
+++ b/test/cli/samples/dir-sourcemap/expected/Main.js
@@ -167,8 +167,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir-sourcemap/expected/Widget.js b/test/cli/samples/dir-sourcemap/expected/Widget.js
index b6019a73fda5..5cdc4cc1baa3 100644
--- a/test/cli/samples/dir-sourcemap/expected/Widget.js
+++ b/test/cli/samples/dir-sourcemap/expected/Widget.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir-subdir/expected/Main.js b/test/cli/samples/dir-subdir/expected/Main.js
index 2778c8c868d6..3468e505f99d 100644
--- a/test/cli/samples/dir-subdir/expected/Main.js
+++ b/test/cli/samples/dir-subdir/expected/Main.js
@@ -167,8 +167,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir-subdir/expected/widget/Widget.js b/test/cli/samples/dir-subdir/expected/widget/Widget.js
index 9282b7ddb4a5..630c96b29464 100644
--- a/test/cli/samples/dir-subdir/expected/widget/Widget.js
+++ b/test/cli/samples/dir-subdir/expected/widget/Widget.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir/expected/Main.js b/test/cli/samples/dir/expected/Main.js
index bbc005da767d..84bc5bd1c89e 100644
--- a/test/cli/samples/dir/expected/Main.js
+++ b/test/cli/samples/dir/expected/Main.js
@@ -167,8 +167,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/dir/expected/Widget.js b/test/cli/samples/dir/expected/Widget.js
index c5981a4c536e..8c475c99f656 100644
--- a/test/cli/samples/dir/expected/Widget.js
+++ b/test/cli/samples/dir/expected/Widget.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/globals/expected/Main.js b/test/cli/samples/globals/expected/Main.js
index 885d7da4bc1f..3d9fc102d064 100644
--- a/test/cli/samples/globals/expected/Main.js
+++ b/test/cli/samples/globals/expected/Main.js
@@ -190,8 +190,8 @@ var Main = (function(answer) { "use strict";
 		assign(this._staged, newState);
 	}
 
-	function _mount(target, anchor) {
-		this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+	function _mount(target, anchor, introing) {
+		this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 	}
 
 	function _differs(a, b) {
diff --git a/test/cli/samples/sourcemap-inline/expected/Main.js b/test/cli/samples/sourcemap-inline/expected/Main.js
index 668ff8b1bfe5..d0632e182e4c 100644
--- a/test/cli/samples/sourcemap-inline/expected/Main.js
+++ b/test/cli/samples/sourcemap-inline/expected/Main.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/sourcemap/expected/Main.js b/test/cli/samples/sourcemap/expected/Main.js
index 95e67187155c..a9669dfa7f3d 100644
--- a/test/cli/samples/sourcemap/expected/Main.js
+++ b/test/cli/samples/sourcemap/expected/Main.js
@@ -165,8 +165,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/cli/samples/store/expected/Main.js b/test/cli/samples/store/expected/Main.js
index 03f4eb521d1e..4ceaa0fc1ab3 100644
--- a/test/cli/samples/store/expected/Main.js
+++ b/test/cli/samples/store/expected/Main.js
@@ -189,8 +189,8 @@ function _stage(newState) {
 	assign(this._staged, newState);
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 function _differs(a, b) {
diff --git a/test/js/samples/action/expected-bundle.js b/test/js/samples/action/expected-bundle.js
index 62c04649ec79..ac1aef0365e2 100644
--- a/test/js/samples/action/expected-bundle.js
+++ b/test/js/samples/action/expected-bundle.js
@@ -133,8 +133,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/bind-width-height/expected-bundle.js b/test/js/samples/bind-width-height/expected-bundle.js
index a4c740e120b5..6f34baae7448 100644
--- a/test/js/samples/bind-width-height/expected-bundle.js
+++ b/test/js/samples/bind-width-height/expected-bundle.js
@@ -165,8 +165,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/collapses-text-around-comments/expected-bundle.js b/test/js/samples/collapses-text-around-comments/expected-bundle.js
index 3f0faa13fc54..5e6cd67b8650 100644
--- a/test/js/samples/collapses-text-around-comments/expected-bundle.js
+++ b/test/js/samples/collapses-text-around-comments/expected-bundle.js
@@ -145,8 +145,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/component-static-array/expected-bundle.js b/test/js/samples/component-static-array/expected-bundle.js
index c2f94398c08b..87fa1c0c2ffb 100644
--- a/test/js/samples/component-static-array/expected-bundle.js
+++ b/test/js/samples/component-static-array/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/component-static-immutable/expected-bundle.js b/test/js/samples/component-static-immutable/expected-bundle.js
index ac9ae4d3f6c9..e76640599b35 100644
--- a/test/js/samples/component-static-immutable/expected-bundle.js
+++ b/test/js/samples/component-static-immutable/expected-bundle.js
@@ -125,8 +125,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/component-static-immutable2/expected-bundle.js b/test/js/samples/component-static-immutable2/expected-bundle.js
index ac9ae4d3f6c9..e76640599b35 100644
--- a/test/js/samples/component-static-immutable2/expected-bundle.js
+++ b/test/js/samples/component-static-immutable2/expected-bundle.js
@@ -125,8 +125,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/component-static/expected-bundle.js b/test/js/samples/component-static/expected-bundle.js
index c839759ecf90..d2980734e9e5 100644
--- a/test/js/samples/component-static/expected-bundle.js
+++ b/test/js/samples/component-static/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/computed-collapsed-if/expected-bundle.js b/test/js/samples/computed-collapsed-if/expected-bundle.js
index c00e61971d8f..61ffbede2457 100644
--- a/test/js/samples/computed-collapsed-if/expected-bundle.js
+++ b/test/js/samples/computed-collapsed-if/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/css-media-query/expected-bundle.js b/test/js/samples/css-media-query/expected-bundle.js
index 80d50457d967..ee22e2a64cdd 100644
--- a/test/js/samples/css-media-query/expected-bundle.js
+++ b/test/js/samples/css-media-query/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js b/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js
index fb563a9db561..0500aa35f6ee 100644
--- a/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js
+++ b/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js
@@ -133,8 +133,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/debug-empty/expected-bundle.js b/test/js/samples/debug-empty/expected-bundle.js
index a9f380840ff0..fa3130a8a6b2 100644
--- a/test/js/samples/debug-empty/expected-bundle.js
+++ b/test/js/samples/debug-empty/expected-bundle.js
@@ -169,8 +169,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var protoDev = {
diff --git a/test/js/samples/debug-foo-bar-baz-things/expected-bundle.js b/test/js/samples/debug-foo-bar-baz-things/expected-bundle.js
index 8965e0ef1b5e..6c53ff74b292 100644
--- a/test/js/samples/debug-foo-bar-baz-things/expected-bundle.js
+++ b/test/js/samples/debug-foo-bar-baz-things/expected-bundle.js
@@ -175,8 +175,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var protoDev = {
diff --git a/test/js/samples/debug-foo/expected-bundle.js b/test/js/samples/debug-foo/expected-bundle.js
index 4b41d50d16b1..c3da12d49604 100644
--- a/test/js/samples/debug-foo/expected-bundle.js
+++ b/test/js/samples/debug-foo/expected-bundle.js
@@ -175,8 +175,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var protoDev = {
diff --git a/test/js/samples/deconflict-builtins/expected-bundle.js b/test/js/samples/deconflict-builtins/expected-bundle.js
index a82fb4ecf72e..975948903581 100644
--- a/test/js/samples/deconflict-builtins/expected-bundle.js
+++ b/test/js/samples/deconflict-builtins/expected-bundle.js
@@ -155,8 +155,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/deconflict-globals/expected-bundle.js b/test/js/samples/deconflict-globals/expected-bundle.js
index 46d2f7bbf804..367ba4ebbe1c 100644
--- a/test/js/samples/deconflict-globals/expected-bundle.js
+++ b/test/js/samples/deconflict-globals/expected-bundle.js
@@ -126,8 +126,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/dev-warning-missing-data-computed/expected-bundle.js b/test/js/samples/dev-warning-missing-data-computed/expected-bundle.js
index 2771b3228d3c..ebb73116411e 100644
--- a/test/js/samples/dev-warning-missing-data-computed/expected-bundle.js
+++ b/test/js/samples/dev-warning-missing-data-computed/expected-bundle.js
@@ -169,8 +169,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var protoDev = {
diff --git a/test/js/samples/do-use-dataset/expected-bundle.js b/test/js/samples/do-use-dataset/expected-bundle.js
index ed3983ea6851..a3bcdf5a1c58 100644
--- a/test/js/samples/do-use-dataset/expected-bundle.js
+++ b/test/js/samples/do-use-dataset/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/dont-use-dataset-in-legacy/expected-bundle.js b/test/js/samples/dont-use-dataset-in-legacy/expected-bundle.js
index 5a011bbca1cc..364250589bf8 100644
--- a/test/js/samples/dont-use-dataset-in-legacy/expected-bundle.js
+++ b/test/js/samples/dont-use-dataset-in-legacy/expected-bundle.js
@@ -141,8 +141,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js b/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js
index 09f6cd44979e..3bc26fa745df 100644
--- a/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js
+++ b/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js
@@ -141,8 +141,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/dynamic-import/expected-bundle.js b/test/js/samples/dynamic-import/expected-bundle.js
index 7283c2cf17fd..1e5fadbce822 100644
--- a/test/js/samples/dynamic-import/expected-bundle.js
+++ b/test/js/samples/dynamic-import/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/each-block-changed-check/expected-bundle.js b/test/js/samples/each-block-changed-check/expected-bundle.js
index faa49a664dce..76c9db7bd171 100644
--- a/test/js/samples/each-block-changed-check/expected-bundle.js
+++ b/test/js/samples/each-block-changed-check/expected-bundle.js
@@ -157,8 +157,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/each-block-keyed-animated/expected-bundle.js b/test/js/samples/each-block-keyed-animated/expected-bundle.js
index a7f5e2280099..cbdf5955d7a1 100644
--- a/test/js/samples/each-block-keyed-animated/expected-bundle.js
+++ b/test/js/samples/each-block-keyed-animated/expected-bundle.js
@@ -460,8 +460,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/each-block-keyed/expected-bundle.js b/test/js/samples/each-block-keyed/expected-bundle.js
index 3643c1c0598c..a326b851aabb 100644
--- a/test/js/samples/each-block-keyed/expected-bundle.js
+++ b/test/js/samples/each-block-keyed/expected-bundle.js
@@ -240,8 +240,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/event-handlers-custom/expected-bundle.js b/test/js/samples/event-handlers-custom/expected-bundle.js
index ea4b3232712d..0dc91184d8bf 100644
--- a/test/js/samples/event-handlers-custom/expected-bundle.js
+++ b/test/js/samples/event-handlers-custom/expected-bundle.js
@@ -133,8 +133,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/head-no-whitespace/expected-bundle.js b/test/js/samples/head-no-whitespace/expected-bundle.js
index 1a1b975edc65..ec9368122cc2 100644
--- a/test/js/samples/head-no-whitespace/expected-bundle.js
+++ b/test/js/samples/head-no-whitespace/expected-bundle.js
@@ -133,8 +133,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/if-block-no-update/expected-bundle.js b/test/js/samples/if-block-no-update/expected-bundle.js
index 6687f56cc386..a22598742f0c 100644
--- a/test/js/samples/if-block-no-update/expected-bundle.js
+++ b/test/js/samples/if-block-no-update/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/if-block-simple/expected-bundle.js b/test/js/samples/if-block-simple/expected-bundle.js
index 2ed0f73584a0..8303b52a5339 100644
--- a/test/js/samples/if-block-simple/expected-bundle.js
+++ b/test/js/samples/if-block-simple/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/inline-style-optimized-multiple/expected-bundle.js b/test/js/samples/inline-style-optimized-multiple/expected-bundle.js
index e6ea18a957ce..9ecaad9e0c63 100644
--- a/test/js/samples/inline-style-optimized-multiple/expected-bundle.js
+++ b/test/js/samples/inline-style-optimized-multiple/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/inline-style-optimized-url/expected-bundle.js b/test/js/samples/inline-style-optimized-url/expected-bundle.js
index 472c72db8adc..6b996880b3c2 100644
--- a/test/js/samples/inline-style-optimized-url/expected-bundle.js
+++ b/test/js/samples/inline-style-optimized-url/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/inline-style-optimized/expected-bundle.js b/test/js/samples/inline-style-optimized/expected-bundle.js
index 40425bcc01e7..8ec022db9ae9 100644
--- a/test/js/samples/inline-style-optimized/expected-bundle.js
+++ b/test/js/samples/inline-style-optimized/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/inline-style-unoptimized/expected-bundle.js b/test/js/samples/inline-style-unoptimized/expected-bundle.js
index ff6bfc070542..0523a5f934c4 100644
--- a/test/js/samples/inline-style-unoptimized/expected-bundle.js
+++ b/test/js/samples/inline-style-unoptimized/expected-bundle.js
@@ -137,8 +137,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/input-files/expected-bundle.js b/test/js/samples/input-files/expected-bundle.js
index b598e619ffc2..5ca168946de5 100644
--- a/test/js/samples/input-files/expected-bundle.js
+++ b/test/js/samples/input-files/expected-bundle.js
@@ -145,8 +145,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/input-range/expected-bundle.js b/test/js/samples/input-range/expected-bundle.js
index 7141e094a31a..529d4bd098c6 100644
--- a/test/js/samples/input-range/expected-bundle.js
+++ b/test/js/samples/input-range/expected-bundle.js
@@ -149,8 +149,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/input-without-blowback-guard/expected-bundle.js b/test/js/samples/input-without-blowback-guard/expected-bundle.js
index 307545663cb5..da527f39c2fa 100644
--- a/test/js/samples/input-without-blowback-guard/expected-bundle.js
+++ b/test/js/samples/input-without-blowback-guard/expected-bundle.js
@@ -145,8 +145,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/legacy-input-type/expected-bundle.js b/test/js/samples/legacy-input-type/expected-bundle.js
index a10dfa137d50..6f8743d56b48 100644
--- a/test/js/samples/legacy-input-type/expected-bundle.js
+++ b/test/js/samples/legacy-input-type/expected-bundle.js
@@ -139,8 +139,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/media-bindings/expected-bundle.js b/test/js/samples/media-bindings/expected-bundle.js
index 33f9f76d092b..4a10fe98580a 100644
--- a/test/js/samples/media-bindings/expected-bundle.js
+++ b/test/js/samples/media-bindings/expected-bundle.js
@@ -149,8 +149,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/non-imported-component/expected-bundle.js b/test/js/samples/non-imported-component/expected-bundle.js
index ec8f608726ca..c2dddb5af7ce 100644
--- a/test/js/samples/non-imported-component/expected-bundle.js
+++ b/test/js/samples/non-imported-component/expected-bundle.js
@@ -135,8 +135,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/select-dynamic-value/expected-bundle.js b/test/js/samples/select-dynamic-value/expected-bundle.js
index 08aae80e9e0c..43cc46e61288 100644
--- a/test/js/samples/select-dynamic-value/expected-bundle.js
+++ b/test/js/samples/select-dynamic-value/expected-bundle.js
@@ -141,8 +141,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/setup-method/expected-bundle.js b/test/js/samples/setup-method/expected-bundle.js
index f36e9584c0c6..9b69a6524ce5 100644
--- a/test/js/samples/setup-method/expected-bundle.js
+++ b/test/js/samples/setup-method/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/svg-title/expected-bundle.js b/test/js/samples/svg-title/expected-bundle.js
index 730857faec14..fe00916e49c4 100644
--- a/test/js/samples/svg-title/expected-bundle.js
+++ b/test/js/samples/svg-title/expected-bundle.js
@@ -141,8 +141,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/title/expected-bundle.js b/test/js/samples/title/expected-bundle.js
index 096430361ef1..9e8603b535d8 100644
--- a/test/js/samples/title/expected-bundle.js
+++ b/test/js/samples/title/expected-bundle.js
@@ -121,8 +121,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/use-elements-as-anchors/expected-bundle.js b/test/js/samples/use-elements-as-anchors/expected-bundle.js
index c86845e7f2aa..020282cb325c 100644
--- a/test/js/samples/use-elements-as-anchors/expected-bundle.js
+++ b/test/js/samples/use-elements-as-anchors/expected-bundle.js
@@ -145,8 +145,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/js/samples/window-binding-scroll/expected-bundle.js b/test/js/samples/window-binding-scroll/expected-bundle.js
index 57ab3aaf7b6b..d177bddaa8da 100644
--- a/test/js/samples/window-binding-scroll/expected-bundle.js
+++ b/test/js/samples/window-binding-scroll/expected-bundle.js
@@ -145,8 +145,8 @@ function callAll(fns) {
 	while (fns && fns.length) fns.shift()();
 }
 
-function _mount(target, anchor) {
-	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null);
+function _mount(target, anchor, introing) {
+	this._fragment[this._fragment.i ? 'i' : 'm'](target, anchor || null, introing);
 }
 
 var proto = {
diff --git a/test/runtime/samples/transition-js-local-nested-await/_config.js b/test/runtime/samples/transition-js-local-nested-await/_config.js
new file mode 100644
index 000000000000..62abb02a88c3
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-await/_config.js
@@ -0,0 +1,33 @@
+let fulfil;
+
+const promise = new Promise(f => {
+	fulfil = f;
+});
+
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false,
+		promise
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+		fulfil();
+
+		return promise.then(() => {
+			const div = target.querySelector('div');
+			assert.equal(div.foo, 0);
+
+			raf.tick(100);
+			assert.equal(div.foo, 1);
+
+			component.set({ x: false });
+			assert.htmlEqual(target.innerHTML, '');
+
+			raf.tick(150);
+			assert.equal(div.foo, 1);
+		});
+	}
+};
diff --git a/test/runtime/samples/transition-js-local-nested-await/main.html b/test/runtime/samples/transition-js-local-nested-await/main.html
new file mode 100644
index 000000000000..fb6c2928601b
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-await/main.html
@@ -0,0 +1,20 @@
+{#if x}
+	{#await promise then value}
+		<div transition:foo|local></div>
+	{/await}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local-nested-component/Widget.html b/test/runtime/samples/transition-js-local-nested-component/Widget.html
new file mode 100644
index 000000000000..7b7728532229
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-component/Widget.html
@@ -0,0 +1,16 @@
+<div transition:foo|local></div>
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local-nested-component/_config.js b/test/runtime/samples/transition-js-local-nested-component/_config.js
new file mode 100644
index 000000000000..5d52dd3f53ed
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-component/_config.js
@@ -0,0 +1,26 @@
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+
+		const div = target.querySelector('div');
+		assert.equal(div.foo, 0);
+
+		raf.tick(100);
+		assert.equal(div.foo, 1);
+
+		component.set({ x: false });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+
+		raf.tick(150);
+		assert.equal(div.foo, 0.5);
+
+		raf.tick(200);
+		assert.htmlEqual(target.innerHTML, '');
+	}
+};
diff --git a/test/runtime/samples/transition-js-local-nested-component/main.html b/test/runtime/samples/transition-js-local-nested-component/main.html
new file mode 100644
index 000000000000..2930f4dc16a7
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-component/main.html
@@ -0,0 +1,13 @@
+{#if x}
+	<Widget/>
+{/if}
+
+<script>
+	import Widget from './Widget.html';
+
+	export default {
+		components: {
+			Widget: './Widget.html'
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local-nested-each-keyed/_config.js b/test/runtime/samples/transition-js-local-nested-each-keyed/_config.js
new file mode 100644
index 000000000000..d1697afa34bc
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-each-keyed/_config.js
@@ -0,0 +1,32 @@
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false,
+		things: ['a']
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+
+		const div1 = target.querySelector('div');
+		assert.equal(div1.foo, undefined);
+
+		raf.tick(100);
+		assert.equal(div1.foo, undefined);
+
+		component.set({ things: ['a', 'b'] });
+		assert.htmlEqual(target.innerHTML, '<div></div><div></div>');
+
+		const div2 = target.querySelector('div:last-child');
+		assert.equal(div1.foo, undefined);
+		assert.equal(div2.foo, 0);
+
+		raf.tick(200);
+		assert.equal(div1.foo, undefined);
+		assert.equal(div2.foo, 1);
+
+		component.set({ x: false });
+		assert.htmlEqual(target.innerHTML, '');
+	},
+};
diff --git a/test/runtime/samples/transition-js-local-nested-each-keyed/main.html b/test/runtime/samples/transition-js-local-nested-each-keyed/main.html
new file mode 100644
index 000000000000..828659173e0d
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-each-keyed/main.html
@@ -0,0 +1,20 @@
+{#if x}
+	{#each things as thing (thing)}
+		<div transition:foo|local></div>
+	{/each}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local-nested-each/_config.js b/test/runtime/samples/transition-js-local-nested-each/_config.js
new file mode 100644
index 000000000000..d1697afa34bc
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-each/_config.js
@@ -0,0 +1,32 @@
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false,
+		things: ['a']
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+
+		const div1 = target.querySelector('div');
+		assert.equal(div1.foo, undefined);
+
+		raf.tick(100);
+		assert.equal(div1.foo, undefined);
+
+		component.set({ things: ['a', 'b'] });
+		assert.htmlEqual(target.innerHTML, '<div></div><div></div>');
+
+		const div2 = target.querySelector('div:last-child');
+		assert.equal(div1.foo, undefined);
+		assert.equal(div2.foo, 0);
+
+		raf.tick(200);
+		assert.equal(div1.foo, undefined);
+		assert.equal(div2.foo, 1);
+
+		component.set({ x: false });
+		assert.htmlEqual(target.innerHTML, '');
+	},
+};
diff --git a/test/runtime/samples/transition-js-local-nested-each/main.html b/test/runtime/samples/transition-js-local-nested-each/main.html
new file mode 100644
index 000000000000..47e62cb12147
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-each/main.html
@@ -0,0 +1,20 @@
+{#if x}
+	{#each things as thing}
+		<div transition:foo|local></div>
+	{/each}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local-nested-if/_config.js b/test/runtime/samples/transition-js-local-nested-if/_config.js
new file mode 100644
index 000000000000..92170fe3cec1
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-if/_config.js
@@ -0,0 +1,41 @@
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false,
+		y: true
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+
+		let div = target.querySelector('div');
+		assert.equal(div.foo, undefined);
+
+		component.set({ y: false });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+		div = target.querySelector('div');
+
+		raf.tick(50);
+		assert.equal(div.foo, 0.5);
+
+		raf.tick(100);
+		assert.htmlEqual(target.innerHTML, '');
+
+		component.set({ x: false, y: true });
+		assert.htmlEqual(target.innerHTML, '');
+
+		component.set({ x: true });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+		div = target.querySelector('div');
+
+		component.set({ y: false });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+
+		raf.tick(150);
+		assert.equal(div.foo, 0.5);
+
+		raf.tick(200);
+		assert.htmlEqual(target.innerHTML, '');
+	},
+};
diff --git a/test/runtime/samples/transition-js-local-nested-if/main.html b/test/runtime/samples/transition-js-local-nested-if/main.html
new file mode 100644
index 000000000000..5111526b3621
--- /dev/null
+++ b/test/runtime/samples/transition-js-local-nested-if/main.html
@@ -0,0 +1,20 @@
+{#if x}
+	{#if y}
+		<div transition:foo|local></div>
+	{/if}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-local/_config.js b/test/runtime/samples/transition-js-local/_config.js
new file mode 100644
index 000000000000..6046a436e32b
--- /dev/null
+++ b/test/runtime/samples/transition-js-local/_config.js
@@ -0,0 +1,41 @@
+export default {
+	nestedTransitions: true,
+
+	data: {
+		x: false,
+		y: true
+	},
+
+	test(assert, component, target, window, raf) {
+		component.set({ x: true });
+
+		let div = target.querySelector('div');
+		assert.equal(div.foo, undefined);
+
+		component.set({ y: false });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+		div = target.querySelector('div');
+
+		raf.tick(50);
+		assert.equal(div.foo, 0.5);
+
+		raf.tick(100);
+		assert.htmlEqual(target.innerHTML, '');
+
+		component.set({ x: false, y: true });
+		assert.htmlEqual(target.innerHTML, '');
+
+		component.set({ x: true });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+		div = target.querySelector('div');
+
+		component.set({ y: false });
+		assert.htmlEqual(target.innerHTML, '<div></div>');
+
+		raf.tick(120);
+		assert.equal(div.foo, 0.8);
+
+		raf.tick(200);
+		assert.htmlEqual(target.innerHTML, '');
+	},
+};
diff --git a/test/runtime/samples/transition-js-local/main.html b/test/runtime/samples/transition-js-local/main.html
new file mode 100644
index 000000000000..5111526b3621
--- /dev/null
+++ b/test/runtime/samples/transition-js-local/main.html
@@ -0,0 +1,20 @@
+{#if x}
+	{#if y}
+		<div transition:foo|local></div>
+	{/if}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>
\ No newline at end of file