How can I check if an element exists in the visible DOM?

It seems some people are landing here, and simply want to know if an element exists (a little bit different to the original question).

That's as simple as using any of the browser's selecting method, and checking it for a truthy value (generally).

For example, if my element had an id of "find-me", I could simply use...

var elementExists = document.getElementById("find-me");

This is specified to either return a reference to the element or null. If you must have a Boolean value, simply toss a !! before the method call.

In addition, you can use some of the many other methods that exist for finding elements, such as (all living off document):

• querySelector()/querySelectorAll()
• getElementsByClassName()
• getElementsByName()

Some of these methods return a NodeList, so be sure to check its length property, because a NodeList is an object, and therefore truthy.

For actually determining if an element exists as part of the visible DOM (like the question originally asked), Csuwldcat provides a better solution than rolling your own (as this answer used to contain). That is, to use the contains() method on DOM elements.

You could use it like so...

document.body.contains(someReferenceToADomElement);

Use getElementById() if it's available.

Also, here's an easy way to do it with jQuery:

if ($('#elementId').length > 0) {  // Exists.}

And if you can't use third-party libraries, just stick to base JavaScript:

var element =  document.getElementById('elementId');if (typeof(element) != 'undefined' && element != null){  // Exists.}

Using the Node.contains DOM API, you can check for the presence of any element in the page (currently in the DOM) quite easily:

document.body.contains(YOUR_ELEMENT_HERE);

CROSS-BROWSER NOTE: the document object in Internet Explorer does not have a contains() method - to ensure cross-browser compatibility, use document.body.contains() instead.