JSHint

JSHint is a community-driven tool that detects errors and potential problems in JavaScript code. Since JSHint is so flexible, you can easily adjust it in the environment you expect your code to execute. JSHint is open source and will always stay this way.

The project aims to help JavaScript developers write complex programs without worrying about typos and language gotchas.

Any code base eventually becomes huge at some point, so simple mistakes — that would not show themselves when written — can become show stoppers and add extra hours of debugging. So, static code analysis tools come into play and help developers spot such problems. JSHint scans a program written in JavaScript and reports about commonly made mistakes and potential bugs. The potential problem could be a syntax error, a bug due to an implicit type conversion, a leaking variable, or something else entirely.

Only 15% of all programs linted on jshint.com pass the JSHint checks. In all other cases, JSHint finds some red flags that could've been bugs or potential problems.

Please note, that while static code analysis tools can spot many different kind of mistakes, it can't detect if your program is correct, fast or has memory leaks. You should always combine tools like JSHint with unit and functional tests as well as with code reviews.