CODEWITHSUNDEEP
javascriptdomdocument
Victor
Victor

Reputation: 17107

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

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?

Upvotes: 55

Views: 152350

Answers (3)

bobince
bobince

Reputation: 536567

getElementById is defined by DOM Level 1 HTML to return null in the case no element is matched.

!==null is the most explicit form of the check, and probably the best, but there is no non-null falsy value that getElementById can return - you can only get null or an always-truthy Element object. So there's no practical difference here between !==null, !=null or the looser if (document.getElementById('xx')).

Upvotes: 30

Peter Rasmussen
Peter Rasmussen

Reputation: 16932

Yes it will return null if it's not present you can try this below in the demo. Both will return true. The first elements exists the second doesn't.

Demo

Html

<div id="xx"></div>

Javascript:

   if (document.getElementById('xx') !=null) 
     console.log('it exists!');

   if (document.getElementById('xxThisisNotAnElementOnThePage') ==null) 
     console.log('does not exist!');

Upvotes: 10

Garrett
Garrett

Reputation: 1688

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.

Upvotes: 103

Related Questions