All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.
Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.
elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
| /* render website with JS and return its rendered output | |
| Syntax: node nodejs_phantomjs_render.js [url] [output {default=stdout}] */ | |
| var system = require('system'), | |
| fs = require('fs'), | |
| page = new WebPage(), | |
| url = system.args[1], | |
| output = system.args[2], | |
| result; |
| # Proxies like unotelly may send more of your traffic through their service than you would like. You can protect your traffic but still use the tunnel if you only send bbc.co.uk DNS lookups to unotelly. | |
| # Here's how to do this in Ubuntu 12.04. The DNS has changed in 12.04 to use NetworkManager, which makes the process more convoluted than it should be. The below instructions could be improved but it'll get you some BBC Olympics coverage. | |
| $ nslookup bbc.co.uk | |
| # you should see a UK IP e.g. 212.58.241.131 | |
| $ vi /etc/NetworkManager/NetworkManager.conf | |
| # comment out dnsmasq | |
| #dns=dnsmasq |