HTML | DOM className Property

In the HTML document, the className property is used to set or return the value of an element’s class attribute. Using this property, the user can change the class of an element to the desired class.

Syntax:

  • returns the className property
  • HTMLElementObject.className;
    
  • sets the className property
  • HTMLElementObject.className = class;
    

    The className specifies the class name of an element. To apply multiple classes, separate them using spaces. As an example, if an element has two classes than we specify them as “classname1 classname2” where classname1 and classname2 are the names of two different classes. The className property returns a string or a space-separated list of classes of an element.



    Example-1: This example set the class for <div> element.

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <!DOCTYPE html>
    <html>
      
    <head>
        <title>
            HTML | DOM className Property
        </title>
        <style>
            .do_style {
                width: 600px;
                height: 100px;
                background-color: lightgreen;
                text-align: center;
                font-size: 25px;
                color: green;
                margin-bottom: 10px;
            }
        </style>
    </head>
      
    <body>
      
        <p>Click the button to set a class for div.</p>
      
        <div id="div1">
            GeeksforGeeks
        </div>
      
        <button onclick="myFunction()">Try it</button>
      
        <script>
            function myFunction() {
                document.getElementById("div1").className =
                    "do_style";
            }
        </script>
      
    </body>
      
    </html>

    chevron_right

    
    

    Output:
    Before Click on The Button:

    Initially

    After Click on The Button:

    After clicking try it button

  • Explanation: The class for < div> element is assigned a value using className property.
  • Example-2: This example get the classes of < div> element.

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <!DOCTYPE html>
    <html>
      
    <head>
        <title>
            HTML | DOM className Property
        </title>
        <style>
            .do_style {
                width: 600px;
                height: 100px;
                background-color: lightgreen;
                text-align: center;
                font-size: 25px;
                color: green;
                margin-bottom: 10px;
            }
        </style>
    </head>
      
    <body>
      
        <p>Click the button to set a class for div.</p>
      
        <div id="div1">
            GeeksforGeeks
        </div>
      
        <button onclick="myFunction()">Try it</button>
      
        <script>
            function myFunction() {
                document.getElementById("div1").className =
                    "do_style";
            }
        </script>
      
    </body>
      
    </html>

    chevron_right

    
    

    Output:

    Before Click on The Button:


    Initially

    After Click on The Button:


    After pressing try it button

    Example-3: This example overwrites the existing class names.

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <!DOCTYPE html>
    <html>
      
    <head>
        <title>
            HTML | DOM className Property
        </title>
        <style>
            .oldstyle {
                width: 300px;
                height: 50px;
                background-color: lightgreen;
                color: green;
                margin-bottom: 10px;
            }
              
            .newstyle {
                width: 400px;
                height: 100px;
                background-color: white;
                text-align: center;
                font-size: 25px;
                color: green;
                margin-bottom: 10px;
            }
        </style>
    </head>
      
    <body>
      
        <p>
          Click the button to change the value of the
          class attribute of div to "newstyle".
        </p>
      
        <div id="div1" class="oldstyle">
            GeeksforGeeks
        </div>
      
        <button onclick="myFunction()">
            Try it
        </button>
      
        <script>
            function myFunction() {
                document.getElementById("div1").className =
                    "newstyle";
            }
        </script>
      
    </body>
      
    </html>

    chevron_right

    
    

    Output:

    Before Click on The Button:


    Initially

    After Click on The Button:


    After pressing try it

    Supported Browsers:

    • Google Chrome
    • Internet Explorer
    • Firefox
    • Opera
    • Safari


    My Personal Notes arrow_drop_up

    Check out this Author's contributed articles.

    If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

    Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.