document.getelementbyId will return null if element is not defined?

javascript domdocument
Victor picture Victor · Mar 27, 2013 · Viewed 116.6k times · Source

In my code, I see this:

if (document.getElementById('xx') !=null) {
    //do stuff
}

if xx element is not defined, will this evaluate to true or false?

Should I write:

if (document.getElementById('xx'))

to be safe?

Answer

Garrett picture Garrett · Mar 27, 2013 
console.log(document.getElementById('xx') ) evaluates to null.

document.getElementById('xx') !=null evaluates to false

You should use document.getElementById('xx') !== null as it is a stronger equality check.

Related questions

Detect Document Height Change

I'm trying to detect when my document height changes. Once it does, I need to run a few functions to help organize my page layout. I'm not looking for window.onresize. I need the entire document, which is larger than …

Read More
Cannot use `document.execCommand('copy');` from developer console

Calling document.execCommand('copy'); from the Chrome developer console returns false every time. Give it a try yourself. Open the console and run it, it never succeeds. Any idea as to why?

Read More
What is anchorNode , baseNode , extentNode and focusNode in the object returned by document.getSelection?

If I make a selection in a html page and I do : var a = document.getSelection() I get an object with four properties : anchorNode baseNode extentNode focusNode the values of first three is the same i.e. the text that …

Read More