One of the toughest things about writing javascript, especially in a Textworks context, is the sheer difficulty of knowing whether the javascript is valid before you even run it.

JSLint is a javascript code quality tool at http://www.jslint.com/ that lets you copy and paste your code into a big textbox and check it for problems. It's saved my sanity many times. Nowadays I quite literally never run any Textworks javascript until it has passed a JSLint test.

N.B. JSLint will check the validity of your javascript from a syntax perspective, meaning it will catch typos, missed semicolons, mismatched brackets and whatnot. It will also warn you about potential problems and weak spots. What it cannot do is tell you whether your code will do what you think it should in a Textworks form: i.e. whether you have expressed your intent correctly.