Question

44

Struggling with classList.add and getElementsByClassName

rated 0 times [ 46] [ 2] / answers: 1 / hits: 20409 / 10 Years ago, sat, june 14, 2014, 12:00:00

I'm trying to add a extra class to some elements with a specific class(input-fieldset).

<fieldset id=pay class=input-fieldset></fieldset>

<fieldset id=address class=input-fieldset></fieldset>

So I did some searches and found this:

var element = document.getElementsByClassName('input-fieldset');

element.classList.add(' input-fieldset-awesome');

I'm trying to add the class input-fieldset-awesome.

But it doesn't work, I get the error:

Uncaught TypeError: Cannot read property 'add' of undefined(anonymous function)

What am I doing wrong?

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trevionbronsonr

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answered 10 Years ago dannyc · Accepted Answer

.getElementsByClassName() returns an HTMLCollection (array of objects) that must be iterated.

The code below will accomplish what you're after.

// Get desired elements

var element = document.getElementsByClassName('input-fieldset');



// Iterate through the retrieved elements and add the necessary class names.

for(var i = 0; i < element.length; i++)

{

    element[i].classList.add('input-fieldset-awesome');

    console.log(element[i].className);

}

Here's a working fiddle to play with.