Ensure deno is installed

Author: timfish

packages/deno/package.json

@@ -24,17 +24,20 @@
     "rollup-plugin-dts": "^6.1.0"
   },
   "scripts": {
-    "prebuild": "deno types > lib.deno.d.ts",
+    "install:deno": "node ./scripts/install-deno.mjs && deno types > lib.deno.d.ts",
+    "prebuild": "yarn install:deno",
     "build": "rollup -c rollup.config.js",
     "postbuild": "deno check build/index.js",
     "build:dev": "yarn build",
     "build:watch": "run-p build:transpile:watch build:types:watch",
     "build:dev:watch": "yarn build:watch",
     "circularDepCheck": "madge --circular src/index.ts",
     "clean": "rimraf build coverage",
+    "prefix": "yarn install:deno",
     "fix": "run-s fix:eslint fix:prettier",
     "fix:eslint": "eslint . --format stylish --fix",
     "fix:prettier": "prettier --write \"{src,test,scripts}/**/**.ts\"",
+    "prelint": "yarn install:deno",
     "lint": "run-s lint:prettier lint:eslint",
     "lint:eslint": "eslint . --format stylish",
     "lint:prettier": "prettier --check \"{src,test,scripts}/**/**.ts\""

packages/deno/scripts/install-deno.mjs

@@ -0,0 +1,31 @@
+import { execSync } from 'child_process';
+
+async function download(url) {
+  try {
+    return await fetch(url).then(res => res.text());
+  } catch (e) {
+    console.error('Failed to download', url, e);
+    process.exit(1);
+  }
+}
+
+try {
+  // Ensure we're using the latest Deno version
+  execSync('deno upgrade', { stdio: 'inherit' });
+} catch (_) {
+  console.error('Deno is not installed. Installing...');
+  if (process.platform === 'win32') {
+    // TODO
+    console.error('Please install Deno manually: https://docs.deno.com/runtime/manual/getting_started/installation');
+    process.exit(1);
+  } else {
+    const script = await download('https://deno.land/x/install/install.sh');
+
+    try {
+      execSync(script, { stdio: 'inherit' });
+    } catch (e) {
+      console.error('Failed to install Deno', e);
+      process.exit(1);
+    }
+  }
+}