Javascript Validator VS JSLint

Try pasting your code into a validator to see if you don't have a typo somewhere: https://beautifytools.com/javascript-validator.php. Source: almost 2 years ago

So everything works fine the way I see it and that error only comes up after a few clicks. Since I'm not a js wizard I did put your script code into a javascript validator and it looks like you're missing a couple of semi colons here and there, maybe that'll fix it. Source: over 2 years ago

UPDATE 8/22/2011: found http://jshint.com, it looks much better than http://jslint.com/. Source: about 2 years ago

Use https://jslint.com to find the unescaped quote or whatever that's invalidating the file. Remember to put quote marks in dialogue as \". Source: over 2 years ago

Ooh! I'm pretty sure I actually know this one! I watched a bunch of Douglas Crockford talk's at Yahoo! Talking about the weirdness of the language he helped develop (such as this one). He also has built JSLint to help pull out code that runs but can have unexpected results. Booleans in JS evaluate if something is truthy or falsy and undefined is falsy (19:20), however a string of "undefined" would be truthy, and... Source: over 2 years ago

For future, just pop your code into an HTML Validator, a JS Linter, or a CSS Linter and it will check for basic stuff like this. There are also plugins in most IDEs for these kind of things which are incredibly useful. Source: about 3 years ago