What are the drawbacks of accessing DOM elements directly by ID?

Question

Today I stumbled upon the possibility to access a DOM element in Javascript simply by its id e.g. like this:

elementid.style.backgroundColor = \"blue\"
         


        

Answer 1

It’s not a part of any standard. Besides, simple variables can be overwriten. Var content could be redeclared in any place of your script, or external library (and, yes, I know global variables are evil, but ppl still use them…) and your script will break.

And, naturally, you cannot use IDs like alert or document etc.