Migrate @storybook/channel-postmessage to TypeScript

lib/channel-postmessage/package.json

@@ -15,7 +15,7 @@
   },
   "license": "MIT",
   "main": "dist/index.js",
-  "jsnext:main": "src/index.js",
+  "types": "dist/index.d.ts",
   "scripts": {
     "prepare": "node ../../scripts/prepare.js"
   },
@@ -24,6 +24,9 @@
     "global": "^4.3.2",
     "json-stringify-safe": "^5.0.1"
   },
+  "devDependencies": {
+    "@types/json-stringify-safe": "^5.0.0"
+  },
   "publishConfig": {
     "access": "public"
   }

lib/channel-postmessage/src/index.js → lib/channel-postmessage/src/index.ts

@@ -1,52 +1,73 @@
 /* eslint-disable no-underscore-dangle */
 
 import { window, document } from 'global';
-import Channel from '@storybook/channels';
+import Channel, { ChannelEvent, ChannelHandler } from '@storybook/channels';
 import stringify from 'json-stringify-safe';
 
+interface RawEvent {
+  data: string;
+}
+
+interface Config {
+  page: 'manager' | 'preview';
+}
+
+interface BufferedEvent {
+  event: ChannelEvent;
+  resolve: (value?: any) => void;
+  reject: (reason?: any) => void;
+}
+
 export const KEY = 'storybook-channel';
 
 export class PostmsgTransport {
-  constructor(config) {
-    this._config = config;
-    this._buffer = [];
-    this._handler = null;
-    window.addEventListener('message', this._handleEvent.bind(this), false);
-    document.addEventListener('DOMContentLoaded', () => this._flush());
+  private buffer: BufferedEvent[];
+  private handler: ChannelHandler;
+
+  constructor(private readonly config: Config) {
+    this.buffer = [];
+    this.handler = null;
+    window.addEventListener('message', this.handleEvent.bind(this), false);
+    document.addEventListener('DOMContentLoaded', () => this.flush());
     // Check whether the config.page parameter has a valid value
     if (config.page !== 'manager' && config.page !== 'preview') {
       throw new Error(`postmsg-channel: "config.page" cannot be "${config.page}"`);
     }
   }
 
-  setHandler(handler) {
-    this._handler = handler;
+  setHandler(handler: ChannelHandler): void {
+    this.handler = handler;
   }
 
-  send(event) {
-    const iframeWindow = this._getWindow();
+  /**
+   * Sends `event` to the associated window. If the window does not yet exist
+   * the event will be stored in a buffer and sent when the window exists.
+   * @param event
+   */
+  send(event: ChannelEvent): Promise<any> {
+    const iframeWindow = this.getWindow();
     if (!iframeWindow) {
       return new Promise((resolve, reject) => {
-        this._buffer.push({ event, resolve, reject });
+        this.buffer.push({ event, resolve, reject });
       });
     }
     const data = stringify({ key: KEY, event });
     iframeWindow.postMessage(data, '*');
     return Promise.resolve(null);
   }
 
-  _flush() {
-    const buffer = this._buffer;
-    this._buffer = [];
+  private flush(): void {
+    const buffer = this.buffer;
+    this.buffer = [];
     buffer.forEach(item => {
       this.send(item.event)
         .then(item.resolve)
         .catch(item.reject);
     });
   }
 
-  _getWindow() {
-    if (this._config.page === 'manager') {
+  private getWindow(): Window {
+    if (this.config.page === 'manager') {
       // FIXME this is a really bad idea! use a better way to do this.
       // This finds the storybook preview iframe to send messages to.
       const iframe = document.getElementById('storybook-preview-iframe');
@@ -58,18 +79,21 @@ export class PostmsgTransport {
     return window.parent;
   }
 
-  _handleEvent(rawEvent) {
+  private handleEvent(rawEvent: RawEvent): void {
     try {
       const { data } = rawEvent;
       const { key, event } = JSON.parse(data);
       if (key === KEY) {
-        this._handler(event);
+        this.handler(event);
       }
     } catch (error) {} // eslint-disable-line
   }
 }
 
-export default function createChannel({ page }) {
+/**
+ * Creates a channel which communicates with an iframe or child window.
+ */
+export default function createChannel({ page }: Config): Channel {
   const transport = new PostmsgTransport({ page });
   return new Channel({ transport });
 }

lib/channel-postmessage/src/typings.d.ts

@@ -0,0 +1 @@
+declare module 'global';

lib/channel-postmessage/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "./src"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["src/**.test.ts"]
+}

yarn.lock

@@ -2349,6 +2349,11 @@
   resolved "https://registry.yarnpkg.com/@types/jest/-/jest-23.3.10.tgz#4897974cc317bf99d4fe6af1efa15957fa9c94de"
   integrity sha512-DC8xTuW/6TYgvEg3HEXS7cu9OijFqprVDXXiOcdOKZCU/5PJNLZU37VVvmZHdtMiGOa8wAA/We+JzbdxFzQTRQ==
 
+"@types/json-stringify-safe@^5.0.0":
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/@types/json-stringify-safe/-/json-stringify-safe-5.0.0.tgz#df34d054419d39323a3730966bacba02ac5e474e"
+  integrity sha512-UUA1sH0RSRROdInuDOA1yoRzbi5xVFD1RHCoOvNRPTNwR8zBkJ/84PZ6NhKVDtKp0FTeIccJCdQz1X2aJPr4uw==
+
 "@types/json5@^0.0.29":
   version "0.0.29"
   resolved "https://registry.yarnpkg.com/@types/json5/-/json5-0.0.29.tgz#ee28707ae94e11d2b827bcbe5270bcea7f3e71ee"