feat(Console): Introduce ConsoleMessage type (#909)

This patch introduces ConsoleMessage type and starts dispatching
it for the 'console' event.

BREAKING CHANGE: this breaks the api of the 'console' event.

Fixes #744.

README.md

@@ -153,7 +153,7 @@ Explore the [API documentation](docs/api.md) and [examples](https://github.com/G
    This is also handy when debugging code in `page.evaluate()`:
 
     ```js
-    page.on('console', (...args) => console.log('PAGE LOG:', ...args));
+    page.on('console', msg => console.log('PAGE LOG:', ...msg.args));
 
     await page.evaluate(() => console.log(`url is ${location.href}`));
     ```

docs/api.md

@@ -99,6 +99,10 @@
     + [dialog.dismiss()](#dialogdismiss)
     + [dialog.message()](#dialogmessage)
     + [dialog.type](#dialogtype)
+  * [class: ConsoleMessage](#class-consolemessage)
+    + [consoleMessage.args](#consolemessageargs)
+    + [consoleMessage.text](#consolemessagetext)
+    + [consoleMessage.type](#consolemessagetype)
   * [class: Frame](#class-frame)
     + [frame.$(selector)](#frameselector)
     + [frame.$$(selector)](#frameselector)
@@ -249,19 +253,19 @@ puppeteer.launch().then(async browser => {
 ```
 
 #### event: 'console'
-- <[string]>
+- <[ConsoleMessage]>
 
 Emitted when JavaScript within the page calls one of console API methods, e.g. `console.log` or `console.dir`. Also emitted if the page throws an error or a warning.
 
 The arguments passed into `console.log` appear as arguments on the event handler.
 
 An example of handling `console` event:
 ```js
-page.on('console', (...args) => {
-  for (let i = 0; i < args.length; ++i)
+page.on('console', msg => {
+  for (let i = 0; i < msg.args.length; ++i)
     console.log(`${i}: ${args[i]}`);
 });
-page.evaluate(() => console.log(5, 'hello', {foo: 'bar'}));
+page.evaluate(() => console.log('hello', 5, {foo: 'bar'}));
 ```
 
 #### event: 'dialog'
@@ -514,7 +518,7 @@ const crypto = require('crypto');
 
 puppeteer.launch().then(async browser => {
   const page = await browser.newPage();
-  page.on('console', console.log);
+  page.on('console', msg => console.log(msg.text));
   await page.exposeFunction('md5', text =>
     crypto.createHash('md5').update(text).digest('hex')
   );
@@ -536,7 +540,7 @@ const fs = require('fs');
 
 puppeteer.launch().then(async browser => {
   const page = await browser.newPage();
-  page.on('console', console.log);
+  page.on('console', msg => console.log(msg.text));
   await page.exposeFunction('readfile', async filePath => {
     return new Promise((resolve, reject) => {
       fs.readFile(filePath, 'utf8', (err, text) => {
@@ -1093,6 +1097,21 @@ puppeteer.launch().then(async browser => {
 
 Dialog's type, could be one of the `alert`, `beforeunload`, `confirm` and `prompt`.
 
+### class: ConsoleMessage
+
+[ConsoleMessage] objects are dispatched by page via the ['console'](#event-console) event.
+
+#### consoleMessage.args
+- <[Array]<[string]>>
+
+#### consoleMessage.text
+- <[string]>
+
+#### consoleMessage.type
+- <[string]>
+
+One of the following values: `'log'`, `'debug'`, `'info'`, `'error'`, `'warning'`, `'dir'`, `'dirxml'`, `'table'`, `'trace'`, `'clear'`, `'startGroup'`, `'startGroupCollapsed'`, `'endGroup'`, `'assert'`, `'profile'`, `'profileEnd'`, `'count'`, `'timeEnd'`.
+
 ### class: Frame
 
 At every point of time, page exposes its current frame tree via the [page.mainFrame()](#pagemainframe) and [frame.childFrames()](#framechildframes) methods.
@@ -1432,6 +1451,7 @@ Contains the URL of the response.
 [stream.Readable]: https://nodejs.org/api/stream.html#stream_class_stream_readable "stream.Readable"
 [Error]: https://nodejs.org/api/errors.html#errors_class_error "Error"
 [Frame]: #class-frame "Frame"
+[ConsoleMessage]: #class-consolemessage "ConsoleMessage"
 [iterator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols "Iterator"
 [Response]: #class-response  "Response"
 [Request]: #class-request  "Request"

lib/Page.js

@@ -313,7 +313,9 @@ class Page extends EventEmitter {
       return;
     }
     const values = await Promise.all(event.args.map(arg => helper.serializeRemoteObject(this._client, arg)));
-    this.emit(Page.Events.Console, ...values);
+    const text = values.join(' ');
+    const message = new ConsoleMessage(event.type, text, values);
+    this.emit(Page.Events.Console, message);
   }
 
   _onDialog(event) {
@@ -875,6 +877,19 @@ Page.Viewport;
  * @property {("Strict"|"Lax")=} sameSite
  */
 
+class ConsoleMessage {
+  /**
+   * @param {string} type
+   * @param {string} text
+   * @param {!Array<*>} args
+   */
+  constructor(type, text, args) {
+    this.type = type;
+    this.text = text;
+    this.args = args;
+  }
+}
+
 
 module.exports = Page;
 helper.tracePublicAPI(Page);

test/test.js

@@ -537,13 +537,15 @@ describe('Page', function() {
 
   describe('Page.Events.Console', function() {
     it('should work', SX(async function() {
-      let commandArgs = [];
-      page.once('console', (...args) => commandArgs = args);
+      let message = null;
+      page.once('console', m => message = m);
       await Promise.all([
-        page.evaluate(() => console.log(5, 'hello', {foo: 'bar'})),
+        page.evaluate(() => console.log('hello', 5, {foo: 'bar'})),
         waitForEvents(page, 'console')
       ]);
-      expect(commandArgs).toEqual([5, 'hello', {foo: 'bar'}]);
+      expect(message.text).toEqual('hello 5 [object Object]');
+      expect(message.type).toEqual('log');
+      expect(message.args).toEqual(['hello', 5, {foo: 'bar'}]);
     }));
     it('should work for different console API calls', SX(async function() {
       const messages = [];
@@ -559,11 +561,14 @@ describe('Page', function() {
           console.error('calling console.error');
           console.log(Promise.resolve('should not wait until resolved!'));
         }),
-        // Wait for 5 events to hit.
+        // Wait for 5 events to hit - console.time is not reported
         waitForEvents(page, 'console', 5)
       ]);
-      expect(messages[0]).toContain('calling console.time');
-      expect(messages.slice(1)).toEqual([
+      expect(messages.map(msg => msg.type)).toEqual([
+        'timeEnd', 'trace', 'dir', 'warning', 'error', 'log'
+      ]);
+      expect(messages[0].text).toContain('calling console.time');
+      expect(messages.slice(1).map(msg => msg.text)).toEqual([
         'calling console.trace',
         'calling console.dir',
         'calling console.warn',
@@ -572,13 +577,13 @@ describe('Page', function() {
       ]);
     }));
     it('should not fail for window object', SX(async function() {
-      let windowObj = null;
-      page.once('console', arg => windowObj = arg);
+      let message = null;
+      page.once('console', msg => message = msg);
       await Promise.all([
         page.evaluate(() => console.error(window)),
         waitForEvents(page, 'console')
       ]);
-      expect(windowObj).toBe('Window');
+      expect(message.text).toBe('Window');
     }));
   });
 

utils/doclint/check_public_api/index.js

@@ -37,6 +37,7 @@ const EXCLUDE_CLASSES = new Set([
 const EXCLUDE_METHODS = new Set([
   'Body.constructor',
   'Browser.constructor',
+  'ConsoleMessage.constructor',
   'Dialog.constructor',
   'ElementHandle.constructor',
   'Frame.constructor',