feat(offscreen-canvas): new type definitiion (#43246)

- definition files
- tests

https://github.com/ai/offscreen-canvas

Thanks!

types/offscreen-canvas/create-worker.d.ts

@@ -0,0 +1,11 @@
+declare function createWorker(
+    canvas: HTMLCanvasElement,
+    workerUrl: string,
+    listener: (ev: MessageEvent) => any,
+): WorkerInterface;
+interface WorkerInterface {
+    post(message: any, transfer: Transferable[]): void;
+    post(message: any, options?: PostMessageOptions): void;
+}
+
+export = createWorker;

types/offscreen-canvas/index.d.ts

@@ -0,0 +1,10 @@
+// Type definitions for offscreen-canvas 0.1
+// Project: https://github.com/ai/offscreen-canvas#readme
+// Definitions by: Peter Błażejewicz <https://github.com/peterblazejewicz>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// Minimum TypeScript Version: 3.5
+
+import createWorker = require('./create-worker');
+import insideWorker = require('./inside-worker');
+
+export { createWorker, insideWorker };

types/offscreen-canvas/inside-worker.d.ts

@@ -0,0 +1,8 @@
+declare function insideWorker(listener: (ev: MessageEvent) => any): WorkerInterface;
+interface WorkerInterface {
+    post(message: any, transfer: Transferable[]): void;
+    post(message: any, options?: PostMessageOptions): void;
+    isWorker: boolean;
+}
+
+export = insideWorker;

types/offscreen-canvas/offscreen-canvas-tests.ts

@@ -0,0 +1,23 @@
+// index.js
+import createWorker = require('offscreen-canvas/create-worker');
+import insideWorker = require('offscreen-canvas/inside-worker');
+
+const workerUrl = document.querySelector<HTMLLinkElement>('[rel=preload][as=script]')!.href;
+const canvas: HTMLCanvasElement = document.querySelector<HTMLCanvasElement>('#canvas')!;
+const button: HTMLButtonElement = document.querySelector<HTMLButtonElement>('#button')!;
+
+const workerOne = createWorker(canvas, workerUrl, e => {
+    // Messages from the worker
+});
+
+button.addEventListener('click', () => {
+    workerOne.post({ message: 'update' });
+});
+
+const workerTwo = insideWorker(e => {
+    if (e.data.canvas) {
+        // Draw on the canvas
+    } else if (e.data.message === 'move') {
+        // Messages from main thread
+    }
+});

types/offscreen-canvas/tsconfig.json

@@ -0,0 +1,24 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6",
+            "DOM"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "offscreen-canvas-tests.ts"
+    ]
+}

types/offscreen-canvas/tslint.json

@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }