However it is the nature of JavaScript itself that scares me. Firstly it's a non-compilable scripting language so you can't catch syntax errors early on. Secondly it throws errors in the weirdest ways making it super hard to debug. Thirdly JavaScript can be used in the following way
parent.document.iframeOne.document.formOne.fieldOne.value
... this can cause serious headaches everytime a page is redesigned.
If there's one thing I learned from doing my final year project (finished product, project web page) it's that JavaScript is evil and should be avoided at any costs. However they are using JavaScript like there's no tomorrow in my new workplace... guess you can't have everything your way.