What is the implementation of GetElementByID()?

Question

Can somebody please explain to me the internal implementation of HTML getElementById() method ? Is it traversing whole DOM tree to find the specified element or is it intelligen

Answer 1

That depends. The method is implemented by each web browser vendor, so the details may be different from one to another and possibly from one version of a browser to another.

I'd suggest taking a look at the source code for a browser such as Mozilla Firefox and see if you can find the implementation.