Using Javascript I\'m trying to test whether or not a DIV with the id \"test_div\" exists in the document.
I\'m using
if (getElementById(\"test_div\")) <
Your case is incorrect in your sample code. You should be invoking getElementById, with a lowercase d. Javascript is case sensitive.
If you're using jquery, make sure to prefix id with a #, like so $("#test_div"), so jquery knows you want to query for an element id.