I am trying to work with a simple WYSIWYG editor. JSLint is saying it has \"Bad escaping of EOL\". Since I am new to javascript I am having a hard time figuring out what it mean
JS didn't support end-of-line escaping with \ until ES5 - you can use multiple strings with a + operator instead, i.e.
"string 1" +
"string 2" +
"string 3"
Re: your other questions:
Use parseInt(n, 10) to force base (aka radix) 10, i.e. decimal 
Use iframe.style.height instead of iframe.style['height']