puppeteer/lib/helper.js
JoelEinbinder bbde8fd1c2 page.evaluate takes a string in addition to function (#135)
This patch improves on page.evaluate to accept a string.
The string can have a trailing '//# sourceURL=' comment which would
name the evaluation to make stacks beautiful.

In order to make sourceURL comments possible, this patch:
- removes wrapping of the client function into `Promise.resolve()`
- stops passing `awaitPromise` parameter to `Runtime.evaluate`
- starts to await promise via the `Runtime.awaitPromise` if the return type of the evaluation
  is promise

closes #118
2017-07-27 12:23:41 -07:00

169 lines
5.5 KiB
JavaScript

/**
* 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.
*/
class Helper {
/**
* @param {function()|string} fun
* @param {!Array<*>} args
* @return {string}
*/
static evaluationString(fun, ...args) {
if (typeof fun === 'string') {
console.assert(args.length === 0, 'Cannot evaluate a string with arguments');
return fun;
}
return `(${fun})(${args.map(x => JSON.stringify(x)).join(',')})`;
}
/**
* @param {!Object} exceptionDetails
* @return {string}
*/
static getExceptionMessage(exceptionDetails) {
if (exceptionDetails.exception)
return exceptionDetails.exception.description;
let message = exceptionDetails.text;
if (exceptionDetails.stackTrace) {
for (let callframe of exceptionDetails.stackTrace.callFrames) {
let location = callframe.url + ':' + callframe.lineNumber + ':' + callframe.columnNumber;
let functionName = callframe.functionName || '<anonymous>';
message += `\n at ${functionName} (${location})`;
}
}
return message;
}
/**
* @param {!Connection} client
* @param {!Object} remoteObject
* @return {!Promise<!Object>}
*/
static async serializeRemoteObject(client, remoteObject) {
if (remoteObject.subtype === 'promise') {
let response = (await client.send('Runtime.awaitPromise', {
promiseObjectId: remoteObject.objectId,
returnByValue: false
}));
Helper.releaseObject(client, remoteObject);
if (response.exceptionDetails)
throw new Error('Evaluation failed: ' + Helper.getExceptionMessage(response.exceptionDetails));
remoteObject = response.result;
}
if (remoteObject.unserializableValue) {
switch (remoteObject.unserializableValue) {
case '-0':
return -0;
case 'NaN':
return NaN;
case 'Infinity':
return Infinity;
case '-Infinity':
return -Infinity;
default:
throw new Error('Unsupported unserializable value: ' + remoteObject.unserializableValue);
}
}
if (!remoteObject.objectId)
return remoteObject.value;
try {
let response = await client.send('Runtime.callFunctionOn', {
objectId: remoteObject.objectId,
functionDeclaration: 'function() { return this; }',
returnByValue: true,
});
return response.result.value;
} catch (e) {
// Return description for unserializable object, e.g. 'window'.
return remoteObject.description;
} finally {
Helper.releaseObject(client, remoteObject);
}
}
/**
* @param {!Connection} client
* @param {!Object} remoteObject
* @return {!Promise}
*/
static async releaseObject(client, remoteObject) {
if (!remoteObject.objectId)
return;
try {
await client.send('Runtime.releaseObject', {objectId: remoteObject.objectId});
} catch (e) {
// Exceptions might happen in case of a page been navigated or closed.
// Swallow these since they are harmless and we don't leak anything in this case.
}
}
/**
* @param {!Object} classType
*/
static tracePublicAPI(classType) {
let className = classType.prototype.constructor.name;
className = className.substring(0, 1).toLowerCase() + className.substring(1);
const debug = require('debug')(`puppeteer:${className}`);
if (!debug.enabled)
return;
for (let methodName of Reflect.ownKeys(classType.prototype)) {
const method = Reflect.get(classType.prototype, methodName);
if (methodName === 'constructor' || typeof methodName !== 'string' || methodName.startsWith('_') || typeof method !== 'function')
continue;
Reflect.set(classType.prototype, methodName, function(...args) {
let argsText = args.map(stringifyArgument).join(', ');
let callsite = `${className}.${methodName}(${argsText})`;
debug(callsite);
return method.call(this, ...args);
});
}
/**
* @param {!Object} arg
* @return {string}
*/
function stringifyArgument(arg) {
if (typeof arg !== 'function')
return JSON.stringify(arg);
let text = arg.toString().split('\n').map(line => line.trim()).join('');
if (text.length > 20)
text = text.substring(0, 20) + '…';
return `"${text}"`;
}
}
/**
* @param {!EventEmitter} emitter
* @param {string} eventName
* @param {function(?)} handler
* @return {{emitter: !EventEmitter, eventName: string, handler: function(?)}}
*/
static addEventListener(emitter, eventName, handler) {
emitter.on(eventName, handler);
return { emitter, eventName, handler };
}
/**
* @param {!Array<{emitter: !EventEmitter, eventName: string, handler: function(?)}>}
*/
static removeEventListeners(listeners) {
for (let listener of listeners)
listener.emitter.removeListener(listener.eventName, listener.handler);
listeners.splice(0, listeners.length);
}
}
module.exports = Helper;