How to remove all classes that begin with a certain string in JavaScript? - GeeksforGeeks

06 Sep, 2019
The task is to remove all the classes of a certain element starting with a specific prefix. Here are a few of the most used techniques discussed. We are going to use JavaScript.
Approach 1:
Select a particular element.
Use .className property to get access to all the classes.
Use .replace() method to replace all the specific classes by space(Which means classes are removed from the element).
In this example, a RegExp is used for replacing.
Example 1: This example using the approach discussed above.
<!DOCTYPE HTML><html>  <head>    <title>        How to remove all classes that      begin with a certain string JavaScript?    </title>    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js">    </script>    <style>        #div {            height: 100px;        }                  .el-color {            color: white;        }                  .el-background {            background: green;        }                  .el-border {            border: 3px solid blue;        }    </style>  </head>  <body id="body" align="center">    <h1 style="color:green;">              GeeksForGeeks          </h1>    <p id="GFG_UP"        style="font-size: 15px;               font-weight: bold;">    </p>    <div id="div"         class="el-color el-background el-border">        Div Element    </div>    <br>    <button onclick="GFG_Fun()">        click here    </button>    <p id="GFG_DOWN"        style="font-size: 20px;              font-weight: bold;              color:green;">    </p>    <script>        var el_up = document.getElementById('GFG_UP');        var el_down = document.getElementById('GFG_DOWN');        el_up.innerHTML =           "Click on the button to remove all "+          "classes starting with certain character.";          function GFG_Fun() {            $('#div')[0].className =               $('#div')[0].className.replace(/\bel.*?\b/g, '');            el_down.innerHTML =               "Every class starting with 'el' is removed from the element.";        }    </script></body>  </html>
Output:
Before clicking on the button:
After clicking on the button:
Approach 2
Select a particular element.
Use .className property to get access to all the classes.
Use .split() method to get all classes as a element.
Use .filter() function to filter out the classes which are not starting with certain character.
Finally, put those classes with the element.
Example 2: This example using the approach discussed above.
<!DOCTYPE HTML><html>  <head>    <title>        How to remove all classes that       begin with a certain string JavaScript?    </title>    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js">    </script>    <style>        #div {            height: 100px;        }                  .el-color {            color: white;        }                  .el-background {            background: green;        }                  .el-border {            border: 3px solid blue;        }    </style>  </head>  <body id="body" align="center">    <h1 style="color:green;">              GeeksForGeeks          </h1>    <p id="GFG_UP"        style="font-size: 15px;               font-weight: bold;">    </p>    <div id="div"          class="el-color el-background el-border">        Div Element    </div>    <br>    <button onclick="GFG_Fun()">        click here    </button>    <p id="GFG_DOWN"        style="font-size: 20px;               font-weight: bold;              color:green;">    </p>    <script>        var el_up = document.getElementById('GFG_UP');        var el_down = document.getElementById('GFG_DOWN');        var el = document.getElementById('div');        el_up.innerHTML = "Click on the button to remove "+          "all classes starting with certain character.";          function GFG_Fun() {            var startsWith = "el";            var classes = el.className.split(" ").filter(function(v) {                return v.lastIndexOf(startsWith, 0) !== 0;            });            el.className = classes.join(" ").trim();            el_down.innerHTML =               "Every class starting with 'el' is removed from the element.";        }    </script></body>  </html>
Output:
Before clicking on the button:
After clicking on the button:
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