classList is a JavaScript property that can be used to work with CSS classes on HTML elements, useful to add, remove, replace and toggle CSS classes on an element. It contains an object list of the class attribute.
Syntax:
element.classList
- If the class attribute is not set or is empty, the element.classList.length returns 0.

classList Methods

The object contained by the classList property has these methods:

Examples with classList

1. Adds two css classes to a <div>:

var div1 = document.getElementById('div1');
div1.classList.add('cls_1', 'cls_2');

2. Removes a css class from a <div>:

var div1 = document.getElementById('div1');
div1.classList.remove('cls_2');

3. Checks if a <div> contains or not a specified css class:

var div1 = document.getElementById('div1');
if(div1.classList.contains('cls_1')) alert('.cls_1 in #div1');
else alert('.cls_1 not in #div1');

4. Replaces class 'foo' with 'bar':

var div1 = document.getElementById('div1');
div1.classList.replace('foo', 'bar');

5. If 'visible' is set removes it, otherwise add it:

var div1 = document.getElementById('div1');
div1.classList.toggle('visible');

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which tag is used to add lists into <ul> and <ol> elements?
<dt> <dd> <li>
<ul>
 <li>http://coursesweb.net/html/</li>
 <li>http://coursesweb.net/css/</li>
</ul>
Which value of the "display" property creates a block box for the content and ads a bullet marker?
block list-item inline-block
.some_class {
  display: list-item;
}
Which instruction converts a JavaScript object into a JSON string.
JSON.parse() JSON.stringify eval()
var obj = {
 "courses": ["php", "javascript", "ajax"]
};
var jsonstr = JSON.stringify(obj);
alert(jsonstr);    // {"courses":["php","javascript","ajax"]}
Indicate the PHP class used to work with HTML and XML content in PHP.
stdClass PDO DOMDocument
$strhtml = '<body><div id="dv1">CoursesWeb.net</div></body>';
$dochtml = new DOMDocument();
$dochtml->loadHTML($strhtml);
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue;    // CoursesWeb.net
classList - Working with CSS classes

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