JavaScript Tip: Rendering Engines

A rendering engine in a browser creates what you see on a screen. There are different ones for each browser.

Firefox Gecko Gecko
Internet Explorer Trident
Chrome Webkit
Safari Webkit
Opera Webkit

When you talk about code working differently in different browsers (modern browsers), you are generally referring to the rendering engine. That’s why you have very few differences in support between Chrome and Safari; they are both built on the same open source rendering engine, Webkit.

Some rendering engines are faster than others, but this also extends to the JavaScript engine in each browser. Just as some rendering engines are better than others, the same can be said about JavaScript engines that are built into the browser. The speeds of these JavaScript engines vary greatly, and this is generally why JavaScript is so slow to execute when compared to other technologies, like CSS.