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 HTML5 tag defines marked text? (can be used to highlight parts of text)
<mark> <embed> <span>
<p>Free corses: <mark>coursesweb.net</mark> for Web Development.</p>
Which CSS pseudo-class adds a style to an element when the mouse is over it?
:focus :hover :active
a:hover {
  font-weight: bold;
  color: #00da01;
}
Click on the function which returns a string value that represents the number rounded to the x digits after the decimal point.
toPrecision(x) toFixed(x) floor(x)
var num = 12.34567;
num = num.toFixed(2);
alert(num);       // 12.35
Indicate the PHP function which reads an entire file into an array.
[) file() readfile()
$arr = file("a_file.txt", FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
var_export($arr);
classList - Working with CSS classes

Last accessed pages

  1. PHP PDO - exec (INSERT, UPDATE, DELETE) MySQL (48760)
  2. PuzzleImg - Script to Create Image Puzzle Game (5076)
  3. Simple Flash animation, Save, Export (1479)
  4. Convert XML to JSON in PHP (9665)
  5. PHP PDO - Select query, fetch (23764)

Popular pages this month

  1. Courses Web: PHP-MySQL JavaScript Node.js Ajax HTML CSS (329)
  2. Register and show online users and visitors (229)
  3. Node.js Move and Copy file (179)
  4. Read Excel file data in PHP - PhpExcelReader (167)
  5. PHP-MySQL free course, online tutorials PHP MySQL code (163)