Exceptions when working with attributes in JavaScript

There is an exception when working with attributes - this is the attribute class. This word is special in JavaScript and therefore we cannot simply write elem.class to read the value of the class attribute. Instead, write elem.className.

Let's look at an example. Let's say we have this input:

<input id="elem" class="aaa bbb">

Let's output the value of the class attribute for our input:

let elem = document.querySelector('#elem'); console.log(elem.className); // shows 'aaa bbb'

There are other exceptions, such as the for attribute. It should be accessed via htmlFor.

A div is given:

<div id="elem" class="content no-gap"></div>

There is also a button. By clicking on the button, read and display the value of the class attribute of our div.

A div is given:

<div id="elem"></div>

There is also a button. By pressing the button, write some class into the class attribute of our div.

Given a div with several CSS classes separated by spaces:

<div id="elem" class="aaa bbb ccc"></div>

There is also a button. On button click, get an array of CSS classes of our div.

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