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helper.js
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helper.js
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/**
* Copyright 2018 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.
*/
const {TimeoutError} = require('./Errors');
/**
* @internal
*/
class Helper {
/**
* @param {Function|string} fun
* @param {!Array<*>} args
* @return {string}
*/
static evaluationString(fun, ...args) {
if (Helper.isString(fun)) {
if (args.length !== 0)
throw new Error('Cannot evaluate a string with arguments');
return /** @type {string} */ (fun);
}
return `(${fun})(${args.map(serializeArgument).join(',')})`;
/**
* @param {*} arg
* @return {string}
*/
function serializeArgument(arg) {
if (Object.is(arg, undefined))
return 'undefined';
return JSON.stringify(arg);
}
}
static promisify(nodeFunction) {
function promisified(...args) {
return new Promise((resolve, reject) => {
function callback(err, ...result) {
if (err)
return reject(err);
if (result.length === 1)
return resolve(result[0]);
return resolve(result);
}
nodeFunction.call(null, ...args, callback);
});
}
return promisified;
}
/**
* @param {!Object} obj
* @return {boolean}
*/
static isNumber(obj) {
return typeof obj === 'number' || obj instanceof Number;
}
/**
* @param {!Object} obj
* @return {boolean}
*/
static isString(obj) {
return typeof obj === 'string' || obj instanceof String;
}
/**
* @param {!NodeJS.EventEmitter} emitter
* @param {(string|symbol)} eventName
* @param {function(?)} handler
* @return {{emitter: !NodeJS.EventEmitter, eventName: (string|symbol), handler: function(?)}}
*/
static addEventListener(emitter, eventName, handler) {
emitter.on(eventName, handler);
return { emitter, eventName, handler };
}
/**
* @param {!Array<{emitter: !NodeJS.EventEmitter, eventName: (string|symbol), handler: function(?)}>} listeners
*/
static removeEventListeners(listeners) {
for (const listener of listeners)
listener.emitter.removeListener(listener.eventName, listener.handler);
listeners.splice(0, listeners.length);
}
/**
* @template T
* @param {!Promise<T>} promise
* @param {string} taskName
* @param {number} timeout
* @return {!Promise<T>}
*/
static async waitWithTimeout(promise, taskName, timeout) {
let reject;
const timeoutError = new TimeoutError(`waiting for ${taskName} failed: timeout ${timeout}ms exceeded`);
const timeoutPromise = new Promise((resolve, x) => reject = x);
const timeoutTimer = setTimeout(() => reject(timeoutError), timeout);
try {
return await Promise.race([promise, timeoutPromise]);
} finally {
clearTimeout(timeoutTimer);
}
}
}
function assert(condition, errorText) {
if (!condition)
throw new Error(errorText);
}
module.exports = {
helper: Helper,
debugError: require('debug')(`puppeteer:error`),
assert,
};