As mentioned before, all SPAs are made with JavaScript, and of course, where you have a lot of JavaScript you can easily get in trouble if you don't take notice of code organization.
We recommend that you use some validation tools such as JSLINT and JSHINT and also a validation tool for JSON files such as JSONLint. The following are the links for these validation tools:
JSLint: http://www.jslint.com/
JSHint: http://www.jshint.com/
JSONLint: http://jsonlint.com/
The main difference between LINT and HINT is that LINT validates indentation and HINT doesn't.