diff --git a/code/async-await/es5/asyncAwaitES5.js b/code/async-await/es5/asyncAwaitES5.js new file mode 100644 index 000000000..059540725 --- /dev/null +++ b/code/async-await/es5/asyncAwaitES5.js @@ -0,0 +1,70 @@ +var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) { + return new (P || (P = Promise))(function (resolve, reject) { + function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } } + function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } } + function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); } + step((generator = generator.apply(thisArg, _arguments || [])).next()); + }); +}; +var __generator = (this && this.__generator) || function (thisArg, body) { + var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g; + return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g; + function verb(n) { return function (v) { return step([n, v]); }; } + function step(op) { + if (f) throw new TypeError("Generator is already executing."); + while (_) try { + if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t; + if (y = 0, t) op = [0, t.value]; + switch (op[0]) { + case 0: case 1: t = op; break; + case 4: _.label++; return { value: op[1], done: false }; + case 5: _.label++; y = op[1]; op = [0]; continue; + case 7: op = _.ops.pop(); _.trys.pop(); continue; + default: + if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; } + if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; } + if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; } + if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; } + if (t[2]) _.ops.pop(); + _.trys.pop(); continue; + } + op = body.call(thisArg, _); + } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; } + if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true }; + } +}; +function delay(milliseconds, count) { + return new Promise(function (resolve) { + setTimeout(function () { + resolve(count); + }, milliseconds); + }); +} +// async function allways return a Promise +function dramaticWelcome() { + return __awaiter(this, void 0, void 0, function () { + var i, count; + return __generator(this, function (_a) { + switch (_a.label) { + case 0: + console.log("Hello"); + i = 0; + _a.label = 1; + case 1: + if (!(i < 5)) return [3 /*break*/, 4]; + return [4 /*yield*/, delay(500, i)]; + case 2: + count = _a.sent(); + console.log(count); + _a.label = 3; + case 3: + i++; + return [3 /*break*/, 1]; + case 4: + console.log("World!"); + return [2 /*return*/]; + } + }); + }); +} +dramaticWelcome(); diff --git a/code/async-await/es5/asyncAwaitES5.ts b/code/async-await/es5/asyncAwaitES5.ts new file mode 100644 index 000000000..ff523e0a4 --- /dev/null +++ b/code/async-await/es5/asyncAwaitES5.ts @@ -0,0 +1,22 @@ +function delay(milliseconds: number, count: number): Promise { + return new Promise(resolve => { + setTimeout(() => { + resolve(count); + }, milliseconds); + }); +} + +// async function allways return a Promise +async function dramaticWelcome(): Promise { + console.log("Hello"); + + for (let i = 0; i < 5; i++) { + // await is converting Promise into number + const count:number = await delay(500, i); + console.log(count); + } + + console.log("World!"); +} + +dramaticWelcome(); \ No newline at end of file diff --git a/code/async-await/es5/tsconfig.json b/code/async-await/es5/tsconfig.json new file mode 100644 index 000000000..b2d585a2e --- /dev/null +++ b/code/async-await/es5/tsconfig.json @@ -0,0 +1,10 @@ +{ + "compilerOptions": { + "target": "es5", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'. */ + "module": "commonjs", /* Specify module code generation: 'commonjs', 'amd', 'system', 'umd' or 'es2015'. */ + "lib": ["dom", "es2015.promise", "es5"] /* Specify library files to be included in the compilation: */ + }, + "files": [ + "./asyncAwaitES5.ts" + ] +} \ No newline at end of file diff --git a/code/async-await/es6/asyncAwaitES6.js b/code/async-await/es6/asyncAwaitES6.js new file mode 100644 index 000000000..1df167d43 --- /dev/null +++ b/code/async-await/es6/asyncAwaitES6.js @@ -0,0 +1,28 @@ +var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) { + return new (P || (P = Promise))(function (resolve, reject) { + function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } } + function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } } + function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); } + step((generator = generator.apply(thisArg, _arguments || [])).next()); + }); +}; +function delay(milliseconds, count) { + return new Promise(resolve => { + setTimeout(() => { + resolve(count); + }, milliseconds); + }); +} +// async function allways return a Promise +function dramaticWelcome() { + return __awaiter(this, void 0, void 0, function* () { + console.log("Hello"); + for (let i = 0; i < 5; i++) { + // await is converting Promise into number + const count = yield delay(500, i); + console.log(count); + } + console.log("World!"); + }); +} +dramaticWelcome(); diff --git a/code/async-await/es6/asyncAwaitES6.ts b/code/async-await/es6/asyncAwaitES6.ts new file mode 100644 index 000000000..ff523e0a4 --- /dev/null +++ b/code/async-await/es6/asyncAwaitES6.ts @@ -0,0 +1,22 @@ +function delay(milliseconds: number, count: number): Promise { + return new Promise(resolve => { + setTimeout(() => { + resolve(count); + }, milliseconds); + }); +} + +// async function allways return a Promise +async function dramaticWelcome(): Promise { + console.log("Hello"); + + for (let i = 0; i < 5; i++) { + // await is converting Promise into number + const count:number = await delay(500, i); + console.log(count); + } + + console.log("World!"); +} + +dramaticWelcome(); \ No newline at end of file diff --git a/code/async-await/es6/tsconfig.json b/code/async-await/es6/tsconfig.json new file mode 100644 index 000000000..40f34b4a7 --- /dev/null +++ b/code/async-await/es6/tsconfig.json @@ -0,0 +1,9 @@ +{ + "compilerOptions": { + "target": "es6", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'. */ + "module": "commonjs" /* Specify module code generation: 'commonjs', 'amd', 'system', 'umd' or 'es2015'. */ + }, + "files": [ + "./asyncAwaitES6.ts" + ] +} \ No newline at end of file diff --git a/docs/async-await.md b/docs/async-await.md index f114c88fc..687225a6e 100644 --- a/docs/async-await.md +++ b/docs/async-await.md @@ -45,4 +45,153 @@ const foo = wrapToReturnPromise(function* () { where the `wrapToReturnPromise` just executes the generator function to get the `generator` and then use `generator.next()`, if the value is a `promise` it would `then`+`catch` the promise and depending upon the result call `generator.next(result)` or `generator.throw(error)`. That's it! + + +### Async Await Support in TypeScript +**Async - Await** has been supported by [TypeScript since version 1.7](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-1-7.html). Asynchronous functions are prefixed with the *async* keyword; *await* suspends the execution until an asynchronous function return promise is fulfilled and unwraps the value from the *Promise* returned. +It was only supported for **target es6** transpiling directly to **ES6 generators**. + +**TypeScript 2.1** [added the capability to ES3 and ES5 run-times](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-1.html), meaning you’ll be free to take advantage of it no matter what environment you’re using. It's important to notice that we can use async / await with TypeScript 2.1 and many browsers are supported, of course, having globally added a **polyfill for Promise**. + +Let's see this **example** and take a look to this code to figure out TypeScript async / await **notation** works: +```ts +function delay(milliseconds: number, count: number): Promise { + return new Promise(resolve => { + setTimeout(() => { + resolve(count); + }, milliseconds); + }); +} + +// async function allways return a Promise +async function dramaticWelcome(): Promise { + console.log("Hello"); + + for (let i = 0; i < 5; i++) { + // await is converting Promise into number + const count:number = await delay(500, i); + console.log(count); + } + + console.log("World!"); +} + +dramaticWelcome(); +``` + +**Transpiling to ES6 (--target es6)** +```js +var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) { + return new (P || (P = Promise))(function (resolve, reject) { + function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } } + function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } } + function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); } + step((generator = generator.apply(thisArg, _arguments || [])).next()); + }); +}; +function delay(milliseconds, count) { + return new Promise(resolve => { + setTimeout(() => { + resolve(count); + }, milliseconds); + }); +} +// async function allways return a Promise +function dramaticWelcome() { + return __awaiter(this, void 0, void 0, function* () { + console.log("Hello"); + for (let i = 0; i < 5; i++) { + // await is converting Promise into number + const count = yield delay(500, i); + console.log(count); + } + console.log("World!"); + }); +} +dramaticWelcome(); +``` +You can see full example [here][asyncawaites6code]. + + +**Transpiling to ES5 (--target es5)** +```js +var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) { + return new (P || (P = Promise))(function (resolve, reject) { + function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } } + function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } } + function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); } + step((generator = generator.apply(thisArg, _arguments || [])).next()); + }); +}; +var __generator = (this && this.__generator) || function (thisArg, body) { + var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g; + return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g; + function verb(n) { return function (v) { return step([n, v]); }; } + function step(op) { + if (f) throw new TypeError("Generator is already executing."); + while (_) try { + if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t; + if (y = 0, t) op = [0, t.value]; + switch (op[0]) { + case 0: case 1: t = op; break; + case 4: _.label++; return { value: op[1], done: false }; + case 5: _.label++; y = op[1]; op = [0]; continue; + case 7: op = _.ops.pop(); _.trys.pop(); continue; + default: + if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; } + if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; } + if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; } + if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; } + if (t[2]) _.ops.pop(); + _.trys.pop(); continue; + } + op = body.call(thisArg, _); + } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; } + if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true }; + } +}; +function delay(milliseconds, count) { + return new Promise(function (resolve) { + setTimeout(function () { + resolve(count); + }, milliseconds); + }); +} +// async function allways return a Promise +function dramaticWelcome() { + return __awaiter(this, void 0, void 0, function () { + var i, count; + return __generator(this, function (_a) { + switch (_a.label) { + case 0: + console.log("Hello"); + i = 0; + _a.label = 1; + case 1: + if (!(i < 5)) return [3 /*break*/, 4]; + return [4 /*yield*/, delay(500, i)]; + case 2: + count = _a.sent(); + console.log(count); + _a.label = 3; + case 3: + i++; + return [3 /*break*/, 1]; + case 4: + console.log("World!"); + return [2 /*return*/]; + } + }); + }); +} +dramaticWelcome(); +``` +You can see full example [here][asyncawaites5code]. + + +**Note**: for both target scenarios, we need to make sure our run-time has an ECMAScript-compliant Promise available globally. That might involve grabbing a polyfill for Promise. We also need to make sure that TypeScript knows Promise exists by setting your lib flag to something like "dom", "es2015" or "dom", "es2015.promise", "es5". +**We can see what browsers DO have Promise support (native and polyfilled) [here](https://kangax.github.io/compat-table/es6/#test-Promise).** + [generators]:./generators.md +[asyncawaites5code]:../code/async-await/es5/asyncAwaitES5.js +[asyncawaites6code]:../code/async-await/es6/asyncAwaitES6.js \ No newline at end of file