JSRef is the missing quick offline reference for the web- and webapp-developer. It contains the current CSS3, ECMA (JavaScript Language Specification), DOM and Canvas API documentation.
JSRef comes with a system wide service "Lookup in JSRef", that integrates into your system and lets you look up the API entry from within any application (e.g. your HTML editor or Safari). And the lookup is scriptable with AppleScript, so you can easily integrate the lookup into your custom workflow. An example AppleScript and Alfred extension for Alfred Power-Users is included.
You can copy syntax snippets or drag the entries into your text editor.
JSRef also contains the WebKit console, so you can try out the syntax right in the JavaScript console (right-click and select "Inspect Element").
The content has been sourced from the MDN Wiki and was edited for JSRef. Though everything has been carefully checked, there is no guarantee about the correctness of the provided information.