http://www.javascriptlint.com/
Here are some common mistakes that JavaScript Lint looks for:
- Missing semicolons at the end of a line.
- Curly braces without an if, for, while, etc.
- Code that is never run because of a return, throw, continue, or break.
- Case statements in a switch that do not have a break statement.
- Leading and trailing decimal points on a number.
- A leading zero that turns a number into octal (base 8).
- Comments within comments.
- Ambiguity whether two adjacent lines are part of the same statement.
- Statements that don't do anything.
