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Nathan Smith
Nathan Smith

Reputation: 37587

How can I change an element's class with JavaScript?

How can I change the class of an HTML element in response to an onclick or any other events using JavaScript?

Upvotes: 3446

Views: 3585244

Answers (30)

Peter Boughton
Peter Boughton

Reputation: 112220

Modern HTML5 Techniques for changing classes

Modern browsers have added classList which provides methods to make it easier to manipulate classes without needing a library:

document.getElementById("MyElement").classList.add('MyClass');

document.getElementById("MyElement").classList.remove('MyClass');

if ( document.getElementById("MyElement").classList.contains('MyClass') )

document.getElementById("MyElement").classList.toggle('MyClass');

Unfortunately, these do not work in Internet Explorer prior to v10, though there is a shim to add support for it to IE8 and IE9, available from this page. It is, though, getting more and more supported.

Simple cross-browser solution

The standard JavaScript way to select an element is using document.getElementById("Id"), which is what the following examples use - you can of course obtain elements in other ways, and in the right situation may simply use this instead - however, going into detail on this is beyond the scope of the answer.

To change all classes for an element:

To replace all existing classes with one or more new classes, set the className attribute:

document.getElementById("MyElement").className = "MyClass";

(You can use a space-delimited list to apply multiple classes.)

To add an additional class to an element:

To add a class to an element, without removing/affecting existing values, append a space and the new classname, like so:

document.getElementById("MyElement").className += " MyClass";

To remove a class from an element:

To remove a single class to an element, without affecting other potential classes, a simple regex replace is required:

document.getElementById("MyElement").className =
   document.getElementById("MyElement").className.replace
      ( /(?:^|\s)MyClass(?!\S)/g , '' )
/* Code wrapped for readability - above is all one statement */

An explanation of this regex is as follows:

(?:^|\s) # Match the start of the string or any single whitespace character

MyClass  # The literal text for the classname to remove

(?!\S)   # Negative lookahead to verify the above is the whole classname
         # Ensures there is no non-space character following
         # (i.e. must be the end of the string or space)

The g flag tells the replace to repeat as required, in case the class name has been added multiple times.

To check if a class is already applied to an element:

The same regex used above for removing a class can also be used as a check as to whether a particular class exists:

if ( document.getElementById("MyElement").className.match(/(?:^|\s)MyClass(?!\S)/) )

Assigning these actions to onClick events:

Whilst it is possible to write JavaScript directly inside the HTML event attributes (such as onClick="this.className+=' MyClass'") this is not recommended behavior. Especially on larger applications, more maintainable code is achieved by separating HTML markup from JavaScript interaction logic.

The first step to achieving this is by creating a function, and calling the function in the onClick attribute, for example:

<script type="text/javascript">
    function changeClass(){
        // Code examples from above
    }
</script>
...
<button onClick="changeClass()">My Button</button>

(It is not required to have this code in script tags, this is simply for the brevity of example, and including the JavaScript in a distinct file may be more appropriate.)

The second step is to move the onClick event out of the HTML and into JavaScript, for example using addEventListener

<script type="text/javascript">
    function changeClass(){
        // Code examples from above
    }

    window.onload = function(){
        document.getElementById("MyElement").addEventListener( 'click', changeClass);
    }
</script>
...
<button id="MyElement">My Button</button>

(Note that the window.onload part is required so that the contents of that function are executed after the HTML has finished loading - without this, the MyElement might not exist when the JavaScript code is called, so that line would fail.)


JavaScript Frameworks and Libraries

The above code is all in standard JavaScript, however, it is common practice to use either a framework or a library to simplify common tasks, as well as benefit from fixed bugs and edge cases that you might not think of when writing your code.

Whilst some people consider it overkill to add a ~50  KB framework for simply changing a class, if you are doing any substantial amount of JavaScript work or anything that might have unusual cross-browser behavior, it is well worth considering.

(Very roughly, a library is a set of tools designed for a specific task, whilst a framework generally contains multiple libraries and performs a complete set of duties.)

The examples above have been reproduced below using jQuery, probably the most commonly used JavaScript library (though there are others worth investigating too).

(Note that $ here is the jQuery object.)

Changing Classes with jQuery:

$('#MyElement').addClass('MyClass');

$('#MyElement').removeClass('MyClass');

if ( $('#MyElement').hasClass('MyClass') )

In addition, jQuery provides a shortcut for adding a class if it doesn't apply, or removing a class that does:

$('#MyElement').toggleClass('MyClass');

### Assigning a function to a click event with jQuery: 
$('#MyElement').click(changeClass);

or, without needing an id:

$(':button:contains(My Button)').click(changeClass);

Upvotes: 4661

moaz ahmad
moaz ahmad

Reputation: 232

To change the class you can use following functiionalities:

HTML:

<button id="myButton">Click me</button>

Javascript:

const button = document.getElementById('myButton');

button.onclick = function() {
  button.classList.add('newClass');
};

CSS:

.newClass {
    background-color: red;
    color: white;
  }

Upvotes: 1

Satish Chandra Gupta
Satish Chandra Gupta

Reputation: 3351

4 actions possible: Add, Remove, Check, and Toggle

Let's see multiple ways for each action.

1. Add class

Method 1: Best way to add a class in the modern browser is using classList.add() method of element.

  • Case 1: Adding single class

    function addClass() {
  let element = document.getElementById('id1');

  // adding class
  element.classList.add('beautify');
}

  • Case 2: Adding multiple class

    To add multiple classes saperate classes by a comma in the add() method

    function addClass() {
  let element = document.getElementById('id1');

  // adding multiple class
  element.classList.add('class1', 'class2', 'class3');
}

Method 2 - You can also add classes to HTML elements using className property.

  • Case 1: Overwriting pre-existing classes When you assign a new class to the className property it overwrites the previous class. 
    function addClass() {
  let element = document.getElementById('id1');

  // adding multiple class
  element.className = 'beautify';
}
  • Case 2: Adding class without overwrite Use += operator for class not to overwrite previous classes. Also, add an extra space before the new class. 
    function addClass() {
  let element = document.getElementById('id1');

  // adding single multiple class
  element.className += ' beautify';
  // adding multiple classes
  element.className += ' class1 class2 class3';
}

2. Remove class

Method 1 - The best way to remove a class from an element is the classList.remove() method.

  • Case 1: Remove single class

    Just pass the class name you want to remove from the element in the method.

    function removeClass() {
  let element = document.getElementById('id1');

  // removing class
  element.classList.remove('beautify');
}

  • Case 2: Remove multiple class

    Pass multiple classes separated by a comma.

    function removeClass() {
  let element = document.getElementById('id1');

  // removing class
  element.classList.remove('class1', 'class2', 'class3');
}

Method 2 - You can also remove class using className method.

  • Case 1: Removing single class If the element has only 1 class and you want to remove it then just assign an empty string to the className method. 
    function removeClass() {
  let element = document.getElementById('id1');

  // removing class
  element.className = '';
}
  • Case 2: Removing multiple class If the element has multiple classes first get all classes from the element using the className property and use replace method and replace desired classes with an empty string and finally assign it to element's className property. 
    function removeClass() {
  let element = document.getElementById('id1');

  // removing class
  element.className = element.className.replace('class1', '');
}

3. Checking class

To check if a class exists in the element you can simply use classList.contains() method. It returns true if the class exists else returns false.

function checkClass() {
  let element = document.getElementById('id1');

  // checking class
  if(element.classList.contains('beautify') {
      alert('Yes! class exists');
  }
}

4. Toggle class

To toggle a class use classList.toggle() method.

function toggleClass() {
    let element = document.getElementById('id1');

    // toggle class
    element.classList.toggle('beautify');
}

Upvotes: 46

uttamcafedeweb
uttamcafedeweb

Reputation: 73

Here is a simple jQuery code to do that:

$(".class1").click(function(argument) {
    $(".parentclass").removeClass("classtoremove");
    setTimeout(function (argument) {
        $(".parentclass").addClass("classtoadd");
    }, 100);
});

Here,

  • Class1 is a listener for an event.
  • The parent class is the class which hosts the class you want to change
  • Classtoremove is the old class you have.
  • Class to add is the new class that you want to add.
  • 100 is the timeout delay during which the class is changed.

Upvotes: -6

gomn
gomn

Reputation: 141

For IE v6-9 (in which classList is not supported and you don't want to use polyfills):

var elem = document.getElementById('some-id');

// don't forget the extra space before the class name
var classList = elem.getAttribute('class') + ' other-class-name';

elem.setAttribute('class', classList);

Upvotes: 6

timbo
timbo

Reputation: 14354

The OP question was How can I change an element's class with JavaScript?

Modern browsers allow you to do this with one line of JavaScript:

document.getElementById('id').classList.replace('span1', 'span2')

The classList attribute provides a DOMTokenList which has a variety of methods. You can operate on an element's classList using simple manipulations like add(), remove() or replace(). Or get very sophisticated and manipulate classes like you would an object or Map with keys(), values(), and entries().

Peter Boughton's answer is a great one, but it's now over a decade old. All modern browsers now support DOMTokenList - see https://caniuse.com/#search=classList and even Internet Explorer 11 supports some DOMTokenList methods.

Upvotes: 9

Jai Prakash
Jai Prakash

Reputation: 59

There is a property, className, in JavaScript to change the name of the class of an HTML element. The existing class value will be replaced with the new one, that you have assigned in className.

<!DOCTYPE html>
<html>
<head>
<title>How can I change the class of an HTML element in JavaScript?</title>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
</head>
<body>
<h1 align="center"><i class="fa fa-home" id="icon"></i></h1><br />

<center><button id="change-class">Change Class</button></center>

<script>
var change_class = document.getElementById("change-class");
change_class.onclick = function()
{
    var icon=document.getElementById("icon");
    icon.className = "fa fa-gear";
}
</script>
</body>
</html>

Credit - How To Change Class Name of an HTML Element in JavaScript

Upvotes: 2

donatso
donatso

Reputation: 108

function classed(el, class_name, add_class) {
  const re = new RegExp("(?:^|\\s)" + class_name + "(?!\\S)", "g");
  if (add_class && !el.className.match(re)) el.className += " " + class_name
  else if (!add_class) el.className = el.className.replace(re, '');
}

Using Peter Boughton's answer, here is a simple cross-browser function to add and remove class.

Add class:

classed(document.getElementById("denis"), "active", true)

Remove class:

classed(document.getElementById("denis"), "active", false)

Upvotes: 2

Kamil Kiełczewski
Kamil Kiełczewski

Reputation: 92627

Try:

element.className='second'


function change(box) { box.className='second' }
.first  { width:  70px; height:  70px; background: #ff0                 }
.second { width: 150px; height: 150px; background: #f00; transition: 1s }
<div onclick="change(this)" class="first">Click me</div>

Upvotes: 6

tfont
tfont

Reputation: 11253

TL;DR:

document.getElementById('id').className = 'class'

OR

document.getElementById('id').classList.add('class');
document.getElementById('id').classList.remove('class');

That's it.

And, if you really want to know the why and educate yourself then I suggest reading Peter Boughton's answer. It's perfect.

Note:

This is possible with (document or event):

  • getElementById()
  • getElementsByClassName()
  • querySelector()
  • querySelectorAll()

Upvotes: 2

Danish Khan
Danish Khan

Reputation: 339

Yes, there are many ways to do this. In ES6 syntax we can achieve easily. Use this code toggle add and remove class.

const tabs=document.querySelectorAll('.menu li');

for(let tab of tabs){

  tab.onclick = function(){

    let activetab = document.querySelectorAll('li.active');

    activetab[0].classList.remove('active')

    tab.classList.add('active');
  }

}
body {
    padding: 20px;
    font-family: sans-serif;
}

ul {
    margin: 20px 0;
    list-style: none;
}

li {
    background: #dfdfdf;
    padding: 10px;
    margin: 6px 0;
    cursor: pointer;
}

li.active {
    background: #2794c7;
    font-weight: bold;
    color: #ffffff;
}
<i>Please click an item:</i>

<ul class="menu">
  <li class="active"><span>Three</span></li>
  <li><span>Two</span></li>
  <li><span>One</span></li>
</ul>

Upvotes: 4

Willem van der Veen
Willem van der Veen

Reputation: 36650

classList DOM API:

A very convenient manner of adding and removing classes is the classList DOM API. This API allows us to select all classes of a specific DOM element in order to modify the list using JavaScript. For example:

const el = document.getElementById("main");
console.log(el.classList);
<div class="content wrapper animated" id="main"></div>

We can observe in the log that we are getting back an object with not only the classes of the element, but also many auxiliary methods and properties. This object inherits from the interface DOMTokenList, an interface which is used in the DOM to represent a set of space separated tokens (like classes).

Example:

const el = document.getElementById('container');

function addClass () {
    el.classList.add('newclass');
}


function replaceClass () {
    el.classList.replace('foo', 'newFoo');
}


function removeClass () {
    el.classList.remove('bar');
}
button{
  margin: 20px;
}

.foo{
  color: red;
}

.newFoo {
  color: blue;
}

.bar{
  background-color: powderblue;
}

.newclass{
  border: 2px solid green;
}
<div class="foo bar" id="container">
  "Sed ut perspiciatis unde omnis
  iste natus error sit voluptatem accusantium doloremque laudantium,
  totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et
  quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam
  voluptatem quia voluptas
 </div>

<button onclick="addClass()">AddClass</button>

<button onclick="replaceClass()">ReplaceClass</button>

<button onclick="removeClass()">removeClass</button>

Upvotes: 4

Eugene Tiurin
Eugene Tiurin

Reputation: 4139

Change an element's class in vanilla JavaScript with Internet Explorer 6 support

You may try to use the node attributes property to keep compatibility with old browsers, even Internet Explorer 6:

function getClassNode(element) {
  for (var i = element.attributes.length; i--;)
    if (element.attributes[i].nodeName === 'class')
      return element.attributes[i];
}

function removeClass(classNode, className) {
  var index, classList = classNode.value.split(' ');
  if ((index = classList.indexOf(className)) > -1) {
    classList.splice(index, 1);
    classNode.value = classList.join(' ');
  }
}

function hasClass(classNode, className) {
  return classNode.value.indexOf(className) > -1;
}

function addClass(classNode, className) {
  if (!hasClass(classNode, className))
    classNode.value += ' ' + className;
}

document.getElementById('message').addEventListener('click', function() {
  var classNode = getClassNode(this);
  var className = hasClass(classNode, 'red') && 'blue' || 'red';

  removeClass(classNode, 'red');
  removeClass(classNode, 'blue');

  addClass(classNode, className);
})
.red {
  color: red;
}
.red:before {
  content: 'I am red! ';
}
.red:after {
  content: ' again';
}
.blue {
  color: blue;
}
.blue:before {
  content: 'I am blue! '
}
<span id="message" class="">Click me</span>

Upvotes: 17

Alireza
Alireza

Reputation: 104870

OK, I think in this case you should use jQuery or write your own Methods in pure JavaScript. My preference is adding my own methods rather than injecting all jQuery to my application if I don't need that for other reasons.

I'd like to do something like below as methods to my JavaScript framework to add few functionalities which handle adding classes, deleting classes, etc. Similar to jQuery, this is fully supported in IE9+. Also my code is written in ES6, so you need to make sure your browser support it or you using something like Babel, otherwise need to use ES5 syntax in your code. Also in this way, we finding element via ID, which means the element needs to have an ID to be selected:

// Simple JavaScript utilities for class management in ES6
var classUtil = {

  addClass: (id, cl) => {
    document.getElementById(id).classList.add(cl);
  },

  removeClass: (id, cl) => {
    document.getElementById(id).classList.remove(cl);
  },

  hasClass: (id, cl) => {
    return document.getElementById(id).classList.contains(cl);
  },

  toggleClass: (id, cl) => {
    document.getElementById(id).classList.toggle(cl);
  }

}

And you can simply use them as below. Imagine your element has id of 'id' and class of 'class'. Make sure you pass them as a string. You can use the utility as below:

classUtil.addClass('myId', 'myClass');
classUtil.removeClass('myId', 'myClass');
classUtil.hasClass('myId', 'myClass');
classUtil.toggleClass('myId', 'myClass');

Upvotes: 5

Ronnie Smith
Ronnie Smith

Reputation: 18585

Just use myElement.classList="new-class" unless you need to maintain other existing classes in which case you can use the classList.add, .remove methods.

var doc = document;
var divOne = doc.getElementById("one");
var goButton = doc.getElementById("go");

goButton.addEventListener("click", function() {
  divOne.classList="blue";
});
div{
  min-height: 48px;
  min-width: 48px;
}
.bordered{
  border: 1px solid black;
}
.green{
  background: green;
}
.blue{
  background: blue;
}
<button id="go">Change Class</button>

<div id="one" class="bordered green">

</div>

Upvotes: 3

kofifus
kofifus

Reputation: 19305

Here's a toggleClass to toggle/add/remove a class on an element:

// If newState is provided add/remove theClass accordingly, otherwise toggle theClass
function toggleClass(elem, theClass, newState) {
    var matchRegExp = new RegExp('(?:^|\\s)' + theClass + '(?!\\S)', 'g');
    var add=(arguments.length>2 ? newState : (elem.className.match(matchRegExp) == null));

    elem.className=elem.className.replace(matchRegExp, ''); // clear all
    if (add) elem.className += ' ' + theClass;
}

See the JSFiddle.

Also see my answer here for creating a new class dynamically.

Upvotes: 13

shingokko
shingokko

Reputation: 412

I would use jQuery and write something like this:

jQuery(function($) {
    $("#some-element").click(function() {
        $(this).toggleClass("clicked");
    });
});

This code adds a function to be called when an element of the id some-element is clicked. The function appends clicked to the element's class attribute if it's not already part of it, and removes it if it's there.

Yes, you do need to add a reference to the jQuery library in your page to use this code, but at least you can feel confident the most functions in the library would work on pretty much all the modern browsers, and it will save you time implementing your own code to do the same.

Upvotes: 19

Ben Flynn
Ben Flynn

Reputation: 18922

Just to add on information from another popular framework, Google Closures, see their dom/classes class:

goog.dom.classes.add(element, var_args)

goog.dom.classes.addRemove(element, classesToRemove, classesToAdd)

goog.dom.classes.remove(element, var_args)

One option for selecting the element is using goog.dom.query with a CSS 3 selector:

var myElement = goog.dom.query("#MyElement")[0];

Upvotes: 26

Andrew Orsich
Andrew Orsich

Reputation: 53695

In one of my old projects that did not use jQuery, I built the following functions for adding, removing and checking if an element has a class:

function hasClass(ele, cls) {
    return ele.className.match(new RegExp('(\\s|^)' + cls + '(\\s|$)'));
}

function addClass(ele, cls) {
    if (!hasClass(ele, cls))
        ele.className += " " + cls;
}

function removeClass(ele, cls) {
    if (hasClass(ele, cls)) {
        var reg = new RegExp('(\\s|^)' + cls + '(\\s|$)');
        ele.className = ele.className.replace(reg, ' ');
    }
}

So, for example, if I want onclick to add some class to the button I can use this:

<script type="text/javascript">
    function changeClass(btn, cls) {
        if(!hasClass(btn, cls)) {
            addClass(btn, cls);
        }
    }
</script>
...
<button onclick="changeClass(this, "someClass")">My Button</button>

By now for sure it would just be better to use jQuery.

Upvotes: 147

Eric Wendelin
Eric Wendelin

Reputation: 44369

You can use node.className like so:

document.getElementById('foo').className = 'bar';

This should work in Internet Explorer 5.5 and up according to PPK.

Upvotes: 108

Tyilo
Tyilo

Reputation: 30142

You could also just do:

document.getElementById('id').classList.add('class');
document.getElementById('id').classList.remove('class');

And to toggle a class (remove if exists else add it):

document.getElementById('id').classList.toggle('class');

Upvotes: 493

Brian Nezhad
Brian Nezhad

Reputation: 6266

THE OPTIONS.

Here is a little style vs. classList examples to get you to see what are the options you have available and how to use classList to do what you want.

style vs. classList

The difference between style and classList is that with style you're adding to the style properties of the element, but classList is kinda controlling the class(es) of the element (add, remove, toggle, contain), I will show you how to use the add and remove method since those are the popular ones.

Style Example

If you want to add margin-top property into an element, you would do in such:

// Get the Element
const el = document.querySelector('#element');

// Add CSS property 
el.style.margintop = "0px"
el.style.margintop = "25px" // This would add a 25px to the top of the element.

classList Example

Let say we have a <div class="class-a class-b">, in this case, we have 2 classes added to our div element already, class-a and class-b, and we want to control what classes remove and what class to add. This is where classList becomes handy.

Remove class-b

// Get the Element
const el = document.querySelector('#element');

// Remove class-b style from the element
el.classList.remove("class-b")

Add class-c

// Get the Element
const el = document.querySelector('#element');

// Add class-b style from the element
el.classList.add("class-c")

Upvotes: 7

Alex Robinson
Alex Robinson

Reputation: 609

A couple of minor notes and tweaks on the previous regexes:

You'll want to do it globally in case the class list has the class name more than once. And, you'll probably want to strip spaces from the ends of the class list and convert multiple spaces to one space to keep from getting runs of spaces. None of these things should be a problem if the only code dinking with the class names uses the regex below and removes a name before adding it. But. Well, who knows who might be dinking with the class name list.

This regex is case insensitive so that bugs in class names may show up before the code is used on a browser that doesn't care about case in class names.

var s = "testing   one   four  one  two";
var cls = "one";
var rg          = new RegExp("(^|\\s+)" + cls + "(\\s+|$)", 'ig');
alert("[" + s.replace(rg, ' ') + "]");
var cls = "test";
var rg          = new RegExp("(^|\\s+)" + cls + "(\\s+|$)", 'ig');
alert("[" + s.replace(rg, ' ') + "]");
var cls = "testing";
var rg          = new RegExp("(^|\\s+)" + cls + "(\\s+|$)", 'ig');
alert("[" + s.replace(rg, ' ') + "]");
var cls = "tWo";
var rg          = new RegExp("(^|\\s+)" + cls + "(\\s+|$)", 'ig');
alert("[" + s.replace(rg, ' ') + "]");

Upvotes: 22

StackSlave
StackSlave

Reputation: 10617

Just thought I'd throw this in:

function inArray(val, ary){
  for(var i=0,l=ary.length; i<l; i++){
    if(ary[i] === val){
      return true;
    }
  }
  return false;
}
function removeClassName(classNameS, fromElement){
  var x = classNameS.split(/\s/), s = fromElement.className.split(/\s/), r = [];
  for(var i=0,l=s.length; i<l; i++){
    if(!iA(s[i], x))r.push(s[i]);
  }
  fromElement.className = r.join(' ');
}
function addClassName(classNameS, toElement){
  var s = toElement.className.split(/\s/);
  s.push(c); toElement.className = s.join(' ');
}

Upvotes: 3

Travis J
Travis J

Reputation: 82307

Wow, surprised there are so many overkill answers here...

<div class="firstClass" onclick="this.className='secondClass'">

Upvotes: 61

Salman Arshad
Salman Arshad

Reputation: 272316

I use the following vanilla JavaScript functions in my code. They use regular expressions and indexOf but do not require quoting special characters in regular expressions.

function addClass(el, cn) {
    var c0 = (" " + el.className + " ").replace(/\s+/g, " "),
        c1 = (" " + cn + " ").replace(/\s+/g, " ");
    if (c0.indexOf(c1) < 0) {
        el.className = (c0 + c1).replace(/\s+/g, " ").replace(/^ | $/g, "");
    }
}

function delClass(el, cn) {
    var c0 = (" " + el.className + " ").replace(/\s+/g, " "),
        c1 = (" " + cn + " ").replace(/\s+/g, " ");
    if (c0.indexOf(c1) >= 0) {
        el.className = c0.replace(c1, " ").replace(/\s+/g, " ").replace(/^ | $/g, "");
    }
}

You can also use element.classList in modern browsers.

Upvotes: 11

moka
moka

Reputation: 23045

As well you could extend HTMLElement object, in order to add methods to add, remove, toggle and check classes (gist):

HTMLElement = typeof(HTMLElement) != 'undefiend' ? HTMLElement : Element;

HTMLElement.prototype.addClass = function(string) {
  if (!(string instanceof Array)) {
    string = string.split(' ');
  }
  for(var i = 0, len = string.length; i < len; ++i) {
    if (string[i] && !new RegExp('(\\s+|^)' + string[i] + '(\\s+|$)').test(this.className)) {
      this.className = this.className.trim() + ' ' + string[i];
    }
  }
}

HTMLElement.prototype.removeClass = function(string) {
  if (!(string instanceof Array)) {
    string = string.split(' ');
  }
  for(var i = 0, len = string.length; i < len; ++i) {
    this.className = this.className.replace(new RegExp('(\\s+|^)' + string[i] + '(\\s+|$)'), ' ').trim();
  }
}

HTMLElement.prototype.toggleClass = function(string) {
  if (string) {
    if (new RegExp('(\\s+|^)' + string + '(\\s+|$)').test(this.className)) {
      this.className = this.className.replace(new RegExp('(\\s+|^)' + string + '(\\s+|$)'), ' ').trim();
    } else {
      this.className = this.className.trim() + ' ' + string;
    }
  }
}

HTMLElement.prototype.hasClass = function(string) {
  return string && new RegExp('(\\s+|^)' + string + '(\\s+|$)').test(this.className);
}

And then just use like this (on click will add or remove class):

document.getElementById('yourElementId').onclick = function() {
  this.toggleClass('active');
}

Here is demo.

Upvotes: 29

alfred
alfred

Reputation: 1018

Here's my version, fully working:

function addHTMLClass(item, classname) {
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    obj.className += " " + classname
}

function removeHTMLClass(item, classname) {
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    var classes = ""+obj.className
    while (classes.indexOf(classname)>-1) {
        classes = classes.replace (classname, "")
    }
    obj.className = classes
}

Usage:

<tr onmouseover='addHTMLClass(this,"clsSelected")'
onmouseout='removeHTMLClass(this,"clsSelected")' >

Upvotes: 14

Hiren Kansara
Hiren Kansara

Reputation: 241

Change an element's CSS class with JavaScript in ASP.NET:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        lbSave.Attributes.Add("onmouseover", "this.className = 'LinkButtonStyle1'")
        lbSave.Attributes.Add("onmouseout", "this.className = 'LinkButtonStyle'")
        lbCancel.Attributes.Add("onmouseover", "this.className = 'LinkButtonStyle1'")
        lbCancel.Attributes.Add("onmouseout", "this.className = 'LinkButtonStyle'")
    End If
End Sub

Upvotes: 22

Gopal Krishna Ranjan
Gopal Krishna Ranjan

Reputation: 878

This is working for me:

function setCSS(eleID) {
    var currTabElem = document.getElementById(eleID);

    currTabElem.setAttribute("class", "some_class_name");
    currTabElem.setAttribute("className", "some_class_name");
}

Upvotes: 43

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