puppeteer/lib/Connection.js

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/**
* Copyright 2017 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
let EventEmitter = require('events');
let WebSocket = require('ws');
let http = require('http');
const COMMAND_TIMEOUT = 10000;
class Connection extends EventEmitter {
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/**
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* @param {number} port
* @param {string} pageId
* @param {!WebSocket} ws
*/
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constructor(port, pageId, ws) {
super();
this._port = port;
this._pageId = pageId;
this._lastId = 0;
/** @type {!Map<number, {resolve: function(*), reject: function(*), method: string}>}*/
this._callbacks = new Map();
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this._ws = ws;
this._ws.on('message', this._onMessage.bind(this));
this._ws.on('close', this._onClose.bind(this));
}
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/**
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* @param {string} method
* @param {(!Object|undefined)} params
* @return {!Promise<?Object>}
*/
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send(method, params = {}) {
let id = ++this._lastId;
let message = JSON.stringify({id, method, params});
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this._ws.send(message);
return new Promise((resolve, reject) => {
this._callbacks.set(id, {resolve, reject, method});
});
}
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/**
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* @param {string} message
*/
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_onMessage(message) {
let object = JSON.parse(message);
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if (object.id && this._callbacks.has(object.id)) {
let callback = this._callbacks.get(object.id);
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this._callbacks.delete(object.id);
if (object.error)
callback.reject(new Error(`Protocol error (${callback.method}): ${object.error.message} ${object.error.data}`));
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else
callback.resolve(object.result);
} else {
console.assert(!object.id);
this.emit(object.method, object.params);
}
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}
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_onClose() {
this._ws.removeAllListeners();
this._ws.close();
}
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/**
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* @return {!Promise}
*/
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async dispose() {
await runJsonCommand(this._port, `close/${this._pageId}`);
}
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/**
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* @param {number} port
* @return {!Promise<!Connection>}
*/
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static async create(port) {
let newTab = await runJsonCommand(port, 'new');
let url = newTab.webSocketDebuggerUrl;
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return new Promise((resolve, reject) => {
let ws = new WebSocket(url, { perMessageDeflate: false });
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ws.on('open', () => resolve(new Connection(port, newTab.id, ws)));
ws.on('error', reject);
});
}
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/**
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* @param {number} port
* @return {!Promise<!Object>}
*/
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static version(port) {
return runJsonCommand(port, 'version');
}
}
/**
* @param {number} port
* @param {string} command
* @return {!Promise<!Object>}
*/
function runJsonCommand(port, command) {
let request = http.get({
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hostname: 'localhost',
port: port,
path: '/json/' + command
}, onResponse);
request.setTimeout(COMMAND_TIMEOUT, onTimeout);
let resolve, reject;
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return new Promise((res, rej) => { resolve = res; reject = rej; });
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function onResponse(response) {
let data = '';
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response.on('data', chunk => data += chunk);
response.on('end', () => {
if (response.statusCode !== 200) {
reject(new Error(`Protocol JSON API error (${command}), status: ${response.statusCode}`));
return;
}
// In the case of 'close' & 'activate' Chromium returns a string rather than JSON: goo.gl/7v27xD
if (data === 'Target is closing' || data === 'Target activated') {
resolve({message: data});
return;
}
try {
resolve(JSON.parse(data));
} catch (e) {
reject(e);
}
});
}
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function onTimeout() {
request.abort();
// Reject on error with code specifically indicating timeout in connection setup.
reject(new Error('Timeout waiting for initial Debugger Protocol connection.'));
}
}
module.exports = Connection;