JSLint

JSLint takes the JavaScript source and scans it. If it finds a problem, it shows a message describing the problem and an approximate location within the source.
Main features:
- Open and check for syntax/performance/security/logic/coding style issues in your .js file.

- Paste/type the JavaScript source code and check for any potential issues immediately.
- Simply one click or press the ⌘L keyboard shortcut, checking is done.
- The lint results are intuitive, including the location and the message describing the issue.
- Double click on a result item will bring you to the specific location where the issue is found.
- Various options are available in the Preferences (⌘, to open the Preferences window).