View gist:f7d355e28c68d82e48a8

Learn JavaScript concepts with the Chrome DevTools

Authored by Peter Rybin , Chrome DevTools team

In this short guide we'll review some new Chrome DevTools features for "function scope" and "internal properties" by exploring some base JavaScript language concepts.


Let's start with closures – one of the most famous things in JS. A closure is a function, that uses variables from outside. See an example:

View gist:4112aa6800d210095e28
driver.executeAsyncScript(function() {
var callback = arguments[arguments.length - 1];
window.onload = function() {
}).then(function() {
//do stuff here
View gist:6e1e3330cf8895616eef
var MongoClient = require('mongodb').MongoClient,
bunyan = require('bunyan'),
log = bunyan.createLogger({
name: 'harvest'
request = require('request')
var url = 'mongodb://localhost:27017/openNews';
MongoClient.connect(url, function(err, db) {
View rule30.html
<!doctype html>
<html lang="en" >
<style type="text/css">
header {
padding: 15px 0;
outline: 1px solid black;
View gist:c28c316c0d9756267324
[cole@localhost cfa]$ python
Earliest Entry in Air Pollutants and Odors happend on 2012-12-05 00:00:00
Latest Entry in Air Pollutants and Odors happend on 2012-12-19 00:00:00
Air Pollutants and Odors has 2 total entries
Earliest Entry in Animals and Pests happend on 2012-01-03 00:00:00
Latest Entry in Animals and Pests happend on 2012-12-28 00:00:00
Animals and Pests has 180 total entries
import csv
import operator
count = 1
previousCategory = None
previousDate = None
previousCount = 1
with open('Violations-2012.csv', 'rb') as csvfile:
spamreader = csv.reader(csvfile, delimiter=',', quotechar='"')
View gist:7850920
View gist:7013529
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "">
<plist version="1.0">
<string>Michael Sheets</string>
View gist:5899513
Access to .ORG WHOIS information is provided to assist persons in
determining the contents of a domain name registration record in the
Public Interest Registry registry database. The data in this record is provided by
Public Interest Registry for informational purposes only, and Public Interest Registry does
guarantee its accuracy. This service is intended only for query-based
access. You agree that you will use this data only for lawful purposes
and that, under no circumstances will you use this data to: (a) allow,
enable, or otherwise support the transmission by e-mail, telephone, or
View cnnAnalyzer.js
var $ = require('cheerio'),
request = require('request')
function gotHTML(err, resp, html) {
if (err) return console.error(err)
var parsedHTML = $.load(html)
parsedHTML('.cnn_mtt1content > ul > li > a ').map(function(i, latest) {
var href = $(latest).attr('href')