classList trong js

HTML DOM classList Property

Element Object

Example

Add the "mystyle" class to a

element: document.getElementById("myDIV").classList.add("mystyle");Try it Yourself »

More "Try it Yourself" examples below.


Definition and Usage

The classList property returns the class name(s) of an element, as a DOMTokenList object.

This property is useful to add, remove and toggle CSS classes on an element.

The classList property is read-only, however, you can modify it by using the add() and remove() methods.

Cross-browser solution: The classList property is not supported in IE9 and earlier. However, you can use the className property or regular expressions for a cross-browser solution (see "More Examples" on the bottom of this page).


Browser Support

The numbers in the table specify the first browser version that fully supports the property. Property classList 8.0 10.0 3.6 5.1 11.5


Syntax element.classList

Properties Property Description length Returns the number of  classes in the list.  This property is read-only

Methods Method Description add(class1, class2, ...) Adds one or more class names to an element.If the  specified class already exist, the class will not be added contains(class) Returns a Boolean value, indicating whether an element has the  specified class name.

Possible values:

  • true - the element contains the specified class name
  • false - the element does not contain the specified class name   item(index) Returns the class name with a specified index number from an  element. Index starts at 0.

    Returns null if the index is  out of range remove(class1, class2, ...) Removes one or more class names from an element.

     Note: Removing a class that does not exist, does NOT  throw an error toggle(class, true|false) Toggles between a class name for an element.

    The first  parameter removes the specified class from an element, and returns  false.
    If the class does not exist, it is added to the element, and the  return value is true.

    The optional second parameter is a Boolean  value that forces the  class to be added or removed, regardless of whether or not it already  existed. For example:

    Remove a class: element.classList.toggle("classToRemove", false);
    Add a class: element.classList.toggle("classToAdd",  true);

    Note: The second parameter is not  supported in Internet Explorer or Opera 12 and earlier.


Technical Details Return Value: A DOMTokenList, containing a list of the class name(s) of an element


More Examples

Example

Add multiple classes to a

element: document.getElementById("myDIV").classList.add("mystyle", "anotherClass", "thirdClass");Try it Yourself »

Example

Remove a class from a

element: document.getElementById("myDIV").classList.remove("mystyle");Try it Yourself »

Example

Remove multiple classes from a

element: document.getElementById("myDIV").classList.remove("mystyle", "anotherClass", "thirdClass");Try it Yourself »

Example

Toggle between two classes for a

element: document.getElementById("myDIV").classList.toggle("newClassName");Try it Yourself »

Example

Get the class name(s) of a

element:
I am a DIV element


var x = document.getElementById("myDIV").classList; Try it Yourself »

Example

Find out how many class names a

element has: var x = document.getElementById("myDIV").classList.length; Try it Yourself »

Example

Get the first class name (index 0) of a

element: var x = document.getElementById("myDIV").classList.item(0); Try it Yourself »

Example

Find out if an element has a "mystyle" class: var x = document.getElementById("myDIV").classList.contains("mystyle"); Try it Yourself »

Example

Find out if an element has a "mystyle" class. If so, remove another class name: var x = document.getElementById("myDIV");

if (x.classList.contains("mystyle")) {
  x.classList.remove("anotherClass");
} else {
  alert("Could not find it.");
}Try it Yourself »

Example

Toggle between classes to create a dropdown button: // Get the button, and when the user clicks on it, execute myFunction
document.getElementById("myBtn").onclick = function() {myFunction()};

/* myFunction toggles between adding and removing the show class, which is used to hide and show the dropdown content */
function myFunction() {
document.getElementById("myDropdown").classList.toggle("show");
}
Try it Yourself »

Fallback Example: add

A cross-browser solution when using the classList.add() method, for IE9 and earlier:  var x, name, arr;
x = document.getElementById("myDIV");
if (x.classList) {
x.classList.add("mystyle");
} else {
name = "mystyle";
arr = x.className.split(" ");
if (arr.indexOf(name) == -1) {
x.className += " " + name;
}
}Try it Yourself »

Fallback Example: remove

A cross-browser solution when using the classList.remove() method, for IE9 and earlier: var x = document.getElementById("myDIV");

if (x.classList) {
  x.classList.remove("mystyle");
} else {
x.className = x.className.replace(/\bmystyle\b/g, ""); // For IE9 and earlier
}Try it Yourself »

Fallback Example: contains

A cross-browser solution when using the classList.contains() method, for IE9 and earlier: var x = document.getElementById("myDIV");

if (x.classList) {
alert(x.classList.contains("mystyle"));
} else {
  alert(/\bmystyle\b/g.test(x.className)); // For IE9 and earlier
}Try it Yourself »

Fallback Example: toggle

A cross-browser solution when using the classList.toggle() method, for IE9: var x = document.getElementById("myDIV");

if (x.classList) {
x.classList.toggle("mystyle");
} else {
  // For IE9
var classes = x.className.split(" ");
var i = classes.indexOf("mystyle");

  if (i >= 0)
classes.splice(i, 1);
else
classes.push("mystyle");
  x.className = classes.join(" ");
}Try it Yourself »

Example

Create a sticky navigation bar:  // Get the navbar
var navbar = document.getElementById("navbar");

// Get the offset position of the navbar
var sticky = navbar.offsetTop;
 
// Add the sticky class to the navbar when you reach its scroll position. Remove the sticky class when you leave the scroll position.
function myFunction() {
if (window.pageYOffset >= sticky) {
navbar.classList.add("sticky")
} else {
navbar.classList.remove("sticky");
}
 }
Try it Yourself »


CSS Tutorial: CSS Syntax

CSS Reference: CSS .class Selector

HTML DOM Reference: HTML DOM className Property

HTML DOM Reference: HTML DOM getElementsByClassName() Method

HTML DOM Reference: HTML DOM Style Object


Element Object

Video liên quan