JavaScript Source Code Analyzer [closed]

Does anyone know of a good, extensible source code analyzer that examines JavaScript files?

In the interest of keeping this question up-to-date, there is a fork of JSLint called JSHint. An explanation of why JSHint was created can be found here, but to summarize:

JSHint is a fork of JSLint, the tool written and maintained by Douglas Crockford. JSLint served me well for quite some time but in the past few months it has gotten uncomfortably opinionated and hostile towards your code. It is quickly transforming from a tool that helps developers to prevent bugs to a tool that makes sure you write your code like Douglas Crockford.

JSLint has historically been the main tool for this, but several more now exist:

• JSHint - a fork of JSLint that is said to be a little less opinionated
• Closure Linter - a linter that checks against the Google Javascript Style Guide
• ESLint - a more flexible tool, but newer, and not yet as stable.