JavaScript - Tools

javascript

http://jsbeautifier.org/
jsbin
http://jsfiddle.net/
http://liveweave.com/
http://www.javascriptlint.com/online_lint.php
http://jsperf.com/

https://flowtype.org/
http://www.sitepoint.com/comparison-javascript-linting-tools
Combine and minify tools
Documentation tools
IDEs
Static analysis tools
Flow diagram tools
Transpilers / Compilers

JavaScript Shell - Syntax checking