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puppeteer-core

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A high-level API to control headless Chrome over the DevTools Protocol

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/** * Copyright 2019 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 fs = require('fs'); const {helper, assert} = require('./helper'); const {LifecycleWatcher} = require('./LifecycleWatcher'); const {TimeoutError} = require('./Errors'); const readFileAsync = helper.promisify(fs.readFile); /** * @unrestricted */ class DOMWorld { /** * @param {!Puppeteer.FrameManager} frameManager * @param {!Puppeteer.Frame} frame * @param {!Puppeteer.TimeoutSettings} timeoutSettings */ constructor(frameManager, frame, timeoutSettings) { this._frameManager = frameManager; this._frame = frame; this._timeoutSettings = timeoutSettings; /** @type {?Promise<!Puppeteer.ElementHandle>} */ this._documentPromise = null; /** @type {!Promise<!Puppeteer.ExecutionContext>} */ this._contextPromise; this._contextResolveCallback = null; this._setContext(null); /** @type {!Set<!WaitTask>} */ this._waitTasks = new Set(); this._detached = false; } /** * @return {!Puppeteer.Frame} */ frame() { return this._frame; } /** * @param {?Puppeteer.ExecutionContext} context */ _setContext(context) { if (context) { this._contextResolveCallback.call(null, context); this._contextResolveCallback = null; for (const waitTask of this._waitTasks) waitTask.rerun(); } else { this._documentPromise = null; this._contextPromise = new Promise(fulfill => { this._contextResolveCallback = fulfill; }); } } _detach() { this._detached = true; for (const waitTask of this._waitTasks) waitTask.terminate(new Error('waitForFunction failed: frame got detached.')); } /** * @return {!Promise<!Puppeteer.ExecutionContext>} */ executionContext() { if (this._detached) throw new Error(`Execution Context is not available in detached frame "${this._frame.url()}" (are you trying to evaluate?)`); return this._contextPromise; } /** * @param {Function|string} pageFunction * @param {!Array<*>} args * @return {!Promise<!Puppeteer.JSHandle>} */ /* async */ evaluateHandle(pageFunction, ...args) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const context = (yield this.executionContext()); return context.evaluateHandle(pageFunction, ...args); });} /** * @param {Function|string} pageFunction * @param {!Array<*>} args * @return {!Promise<*>} */ /* async */ evaluate(pageFunction, ...args) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const context = (yield this.executionContext()); return context.evaluate(pageFunction, ...args); });} /** * @param {string} selector * @return {!Promise<?Puppeteer.ElementHandle>} */ /* async */ $(selector) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield this._document()); const value = (yield document.$(selector)); return value; });} /** * @return {!Promise<!Puppeteer.ElementHandle>} */ /* async */ _document() {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ if (this._documentPromise) return this._documentPromise; this._documentPromise = this.executionContext().then(/* async */ context => {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield context.evaluateHandle('document')); return document.asElement(); });}); return this._documentPromise; });} /** * @param {string} expression * @return {!Promise<!Array<!Puppeteer.ElementHandle>>} */ /* async */ $x(expression) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield this._document()); const value = (yield document.$x(expression)); return value; });} /** * @param {string} selector * @param {Function|string} pageFunction * @param {!Array<*>} args * @return {!Promise<(!Object|undefined)>} */ /* async */ $eval(selector, pageFunction, ...args) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield this._document()); return document.$eval(selector, pageFunction, ...args); });} /** * @param {string} selector * @param {Function|string} pageFunction * @param {!Array<*>} args * @return {!Promise<(!Object|undefined)>} */ /* async */ $$eval(selector, pageFunction, ...args) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield this._document()); const value = (yield document.$$eval(selector, pageFunction, ...args)); return value; });} /** * @param {string} selector * @return {!Promise<!Array<!Puppeteer.ElementHandle>>} */ /* async */ $$(selector) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const document = (yield this._document()); const value = (yield document.$$(selector)); return value; });} /** * @return {!Promise<String>} */ /* async */ content() {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ return (yield this.evaluate(() => { let retVal = ''; if (document.doctype) retVal = new XMLSerializer().serializeToString(document.doctype); if (document.documentElement) retVal += document.documentElement.outerHTML; return retVal; })); });} /** * @param {string} html * @param {!{timeout?: number, waitUntil?: string|!Array<string>}=} options */ /* async */ setContent(html, options = {}) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const { waitUntil = ['load'], timeout = this._timeoutSettings.navigationTimeout(), } = options; // We rely upon the fact that document.open() will reset frame lifecycle with "init" // lifecycle event. @see https://crrev.com/608658 (yield this.evaluate(html => { document.open(); document.write(html); document.close(); }, html)); const watcher = new LifecycleWatcher(this._frameManager, this._frame, waitUntil, timeout); const error = (yield Promise.race([ watcher.timeoutOrTerminationPromise(), watcher.lifecyclePromise(), ])); watcher.dispose(); if (error) throw error; });} /** * @param {!{url?: string, path?: string, content?: string, type?: string}} options * @return {!Promise<!Puppeteer.ElementHandle>} */ /* async */ addScriptTag(options) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const { url = null, path = null, content = null, type = '' } = options; if (url !== null) { try { const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addScriptUrl, url, type))).asElement(); } catch (error) { throw new Error(`Loading script from ${url} failed`); } } if (path !== null) { let contents = (yield readFileAsync(path, 'utf8')); contents += '//# sourceURL=' + path.replace(/\n/g, ''); const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addScriptContent, contents, type))).asElement(); } if (content !== null) { const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addScriptContent, content, type))).asElement(); } throw new Error('Provide an object with a `url`, `path` or `content` property'); /** * @param {string} url * @param {string} type * @return {!Promise<!HTMLElement>} */ /* async */ function addScriptUrl(url, type) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const script = document.createElement('script'); script.src = url; if (type) script.type = type; const promise = new Promise((res, rej) => { script.onload = res; script.onerror = rej; }); document.head.appendChild(script); (yield promise); return script; });} /** * @param {string} content * @param {string} type * @return {!HTMLElement} */ function addScriptContent(content, type = 'text/javascript') { const script = document.createElement('script'); script.type = type; script.text = content; let error = null; script.onerror = e => error = e; document.head.appendChild(script); if (error) throw error; return script; } });} /** * @param {!{url?: string, path?: string, content?: string}} options * @return {!Promise<!Puppeteer.ElementHandle>} */ /* async */ addStyleTag(options) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const { url = null, path = null, content = null } = options; if (url !== null) { try { const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addStyleUrl, url))).asElement(); } catch (error) { throw new Error(`Loading style from ${url} failed`); } } if (path !== null) { let contents = (yield readFileAsync(path, 'utf8')); contents += '/*# sourceURL=' + path.replace(/\n/g, '') + '*/'; const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addStyleContent, contents))).asElement(); } if (content !== null) { const context = (yield this.executionContext()); return ((yield context.evaluateHandle(addStyleContent, content))).asElement(); } throw new Error('Provide an object with a `url`, `path` or `content` property'); /** * @param {string} url * @return {!Promise<!HTMLElement>} */ /* async */ function addStyleUrl(url) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const link = document.createElement('link'); link.rel = 'stylesheet'; link.href = url; const promise = new Promise((res, rej) => { link.onload = res; link.onerror = rej; }); document.head.appendChild(link); (yield promise); return link; });} /** * @param {string} content * @return {!Promise<!HTMLElement>} */ /* async */ function addStyleContent(content) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const style = document.createElement('style'); style.type = 'text/css'; style.appendChild(document.createTextNode(content)); const promise = new Promise((res, rej) => { style.onload = res; style.onerror = rej; }); document.head.appendChild(style); (yield promise); return style; });} });} /** * @param {string} selector * @param {!{delay?: number, button?: "left"|"right"|"middle", clickCount?: number}=} options */ /* async */ click(selector, options) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const handle = (yield this.$(selector)); assert(handle, 'No node found for selector: ' + selector); (yield handle.click(options)); (yield handle.dispose()); });} /** * @param {string} selector */ /* async */ focus(selector) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const handle = (yield this.$(selector)); assert(handle, 'No node found for selector: ' + selector); (yield handle.focus()); (yield handle.dispose()); });} /** * @param {string} selector */ /* async */ hover(selector) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const handle = (yield this.$(selector)); assert(handle, 'No node found for selector: ' + selector); (yield handle.hover()); (yield handle.dispose()); });} /** * @param {string} selector * @param {!Array<string>} values * @return {!Promise<!Array<string>>} */ select(selector, ...values){ for (const value of values) assert(helper.isString(value), 'Values must be strings. Found value "' + value + '" of type "' + (typeof value) + '"'); return this.$eval(selector, (element, values) => { if (element.nodeName.toLowerCase() !== 'select') throw new Error('Element is not a <select> element.'); const options = Array.from(element.options); element.value = undefined; for (const option of options) { option.selected = values.includes(option.value); if (option.selected && !element.multiple) break; } element.dispatchEvent(new Event('input', { 'bubbles': true })); element.dispatchEvent(new Event('change', { 'bubbles': true })); return options.filter(option => option.selected).map(option => option.value); }, values); } /** * @param {string} selector */ /* async */ tap(selector) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const handle = (yield this.$(selector)); assert(handle, 'No node found for selector: ' + selector); (yield handle.tap()); (yield handle.dispose()); });} /** * @param {string} selector * @param {string} text * @param {{delay: (number|undefined)}=} options */ /* async */ type(selector, text, options) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const handle = (yield this.$(selector)); assert(handle, 'No node found for selector: ' + selector); (yield handle.type(text, options)); (yield handle.dispose()); });} /** * @param {string} selector * @param {!{visible?: boolean, hidden?: boolean, timeout?: number}=} options * @return {!Promise<?Puppeteer.ElementHandle>} */ waitForSelector(selector, options) { return this._waitForSelectorOrXPath(selector, false, options); } /** * @param {string} xpath * @param {!{visible?: boolean, hidden?: boolean, timeout?: number}=} options * @return {!Promise<?Puppeteer.ElementHandle>} */ waitForXPath(xpath, options) { return this._waitForSelectorOrXPath(xpath, true, options); } /** * @param {Function|string} pageFunction * @param {!{polling?: string|number, timeout?: number}=} options * @return {!Promise<!Puppeteer.JSHandle>} */ waitForFunction(pageFunction, options = {}, ...args) { const { polling = 'raf', timeout = this._timeoutSettings.timeout(), } = options; return new WaitTask(this, pageFunction, 'function', polling, timeout, ...args).promise; } /** * @return {!Promise<string>} */ /* async */ title() {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ return this.evaluate(() => document.title); });} /** * @param {string} selectorOrXPath * @param {boolean} isXPath * @param {!{visible?: boolean, hidden?: boolean, timeout?: number}=} options * @return {!Promise<?Puppeteer.ElementHandle>} */ /* async */ _waitForSelectorOrXPath(selectorOrXPath, isXPath, options = {}) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const { visible: waitForVisible = false, hidden: waitForHidden = false, timeout = this._timeoutSettings.timeout(), } = options; const polling = waitForVisible || waitForHidden ? 'raf' : 'mutation'; const title = `${isXPath ? 'XPath' : 'selector'} "${selectorOrXPath}"${waitForHidden ? ' to be hidden' : ''}`; const waitTask = new WaitTask(this, predicate, title, polling, timeout, selectorOrXPath, isXPath, waitForVisible, waitForHidden); const handle = (yield waitTask.promise); if (!handle.asElement()) { (yield handle.dispose()); return null; } return handle.asElement(); /** * @param {string} selectorOrXPath * @param {boolean} isXPath * @param {boolean} waitForVisible * @param {boolean} waitForHidden * @return {?Node|boolean} */ function predicate(selectorOrXPath, isXPath, waitForVisible, waitForHidden) { const node = isXPath ? document.evaluate(selectorOrXPath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue : document.querySelector(selectorOrXPath); if (!node) return waitForHidden; if (!waitForVisible && !waitForHidden) return node; const element = /** @type {Element} */ (node.nodeType === Node.TEXT_NODE ? node.parentElement : node); const style = window.getComputedStyle(element); const isVisible = style && style.visibility !== 'hidden' && hasVisibleBoundingBox(); const success = (waitForVisible === isVisible || waitForHidden === !isVisible); return success ? node : null; /** * @return {boolean} */ function hasVisibleBoundingBox() { const rect = element.getBoundingClientRect(); return !!(rect.top || rect.bottom || rect.width || rect.height); } } });} } class WaitTask { /** * @param {!DOMWorld} domWorld * @param {Function|string} predicateBody * @param {string|number} polling * @param {number} timeout * @param {!Array<*>} args */ constructor(domWorld, predicateBody, title, polling, timeout, ...args) { if (helper.isString(polling)) assert(polling === 'raf' || polling === 'mutation', 'Unknown polling option: ' + polling); else if (helper.isNumber(polling)) assert(polling > 0, 'Cannot poll with non-positive interval: ' + polling); else throw new Error('Unknown polling options: ' + polling); this._domWorld = domWorld; this._polling = polling; this._timeout = timeout; this._predicateBody = helper.isString(predicateBody) ? 'return (' + predicateBody + ')' : 'return (' + predicateBody + ')(...args)'; this._args = args; this._runCount = 0; domWorld._waitTasks.add(this); this.promise = new Promise((resolve, reject) => { this._resolve = resolve; this._reject = reject; }); // Since page navigation requires us to re-install the pageScript, we should track // timeout on our end. if (timeout) { const timeoutError = new TimeoutError(`waiting for ${title} failed: timeout ${timeout}ms exceeded`); this._timeoutTimer = setTimeout(() => this.terminate(timeoutError), timeout); } this.rerun(); } /** * @param {!Error} error */ terminate(error) { this._terminated = true; this._reject(error); this._cleanup(); } /* async */ rerun() {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const runCount = ++this._runCount; /** @type {?Puppeteer.JSHandle} */ let success = null; let error = null; try { success = (yield ((yield this._domWorld.executionContext())).evaluateHandle(waitForPredicatePageFunction, this._predicateBody, this._polling, this._timeout, ...this._args)); } catch (e) { error = e; } if (this._terminated || runCount !== this._runCount) { if (success) (yield success.dispose()); return; } // Ignore timeouts in pageScript - we track timeouts ourselves. // If the frame's execution context has already changed, `frame.evaluate` will // throw an error - ignore this predicate run altogether. if (!error && (yield this._domWorld.evaluate(s => !s, success).catch(e => true))) { (yield success.dispose()); return; } // When the page is navigated, the promise is rejected. // We will try again in the new execution context. if (error && error.message.includes('Execution context was destroyed')) return; // We could have tried to evaluate in a context which was already // destroyed. if (error && error.message.includes('Cannot find context with specified id')) return; if (error) this._reject(error); else this._resolve(success); this._cleanup(); });} _cleanup() { clearTimeout(this._timeoutTimer); this._domWorld._waitTasks.delete(this); this._runningTask = null; } } /** * @param {string} predicateBody * @param {string} polling * @param {number} timeout * @return {!Promise<*>} */ /* async */ function waitForPredicatePageFunction(predicateBody, polling, timeout, ...args) {return (fn => { const gen = fn.call(this); return new Promise((resolve, reject) => { function step(key, arg) { let info, value; try { info = gen[key](arg); value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then( value => { step('next', value); }, err => { step('throw', err); }); } } return step('next'); }); })(function*(){ const predicate = new Function('...args', predicateBody); let timedOut = false; if (timeout) setTimeout(() => timedOut = true, timeout); if (polling === 'raf') return (yield pollRaf()); if (polling === 'mutation') return (yield pollMutation()); if (typeof polling === 'number') return (yield pollInterval(polling)); /** * @return {!Promise<*>} */ function pollMutation() { const success = predicate.apply(null, args); if (success) return Promise.resolve(success); let fulfill; const result = new Promise(x => fulfill = x); const observer = new MutationObserver(mutations => { if (timedOut) { observer.disconnect(); fulfill(); } const success = predicate.apply(null, args); if (success) { observer.disconnect(); fulfill(success); } }); observer.observe(document, { childList: true, subtree: true, attributes: true }); return result; } /** * @return {!Promise<*>} */ function pollRaf() { let fulfill; const result = new Promise(x => fulfill = x); onRaf(); return result; function onRaf() { if (timedOut) { fulfill(); return; } const success = predicate.apply(null, args); if (success) fulfill(success); else requestAnimationFrame(onRaf); } } /** * @param {number} pollInterval * @return {!Promise<*>} */ function pollInterval(pollInterval) { let fulfill; const result = new Promise(x => fulfill = x); onTimeout(); return result; function onTimeout() { if (timedOut) { fulfill(); return; } const success = predicate.apply(null, args); if (success) fulfill(success); else setTimeout(onTimeout, pollInterval); } } });} module.exports = {DOMWorld};