Posted By: Blankman

I have an element that already has a class:

<div class="someclass">
    <img ... id="image1" name="image1" />
</div>

Now, I want to create a JavaScript function that will add a class to the div (not replace, but add).

How can I do that?

Solution

If you’re only targeting modern browsers:

Use element.classList.add to add a class:

element.classList.add("my-class");

And element.classList.remove to remove a class:

element.classList.remove("my-class");

If you need to support Internet Explorer 9 or lower:

Add a space plus the name of your new class to the className property of the element. First, put an id on the element so you can easily get a reference.

<div id="div1" class="someclass">
    <img ... id="image1" name="image1" />
</div>

Then

var d = document.getElementById("div1");
d.className += " otherclass";

Note the space before otherclass. It’s important to include the space otherwise it compromises existing classes that come before it in the class list.

See also element.className on MDN.

Answered By: Ishmael

Disclaimer: This content is shared under creative common license cc-by-sa 3.0. It is generated from StackExchange Website Network.