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How to add/update an attribute to an HTML element using JavaScript?

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To add/update an attribute to an HTML element using JavaScript, we have multiple approaches. In this article, we are going to learn how to add/update an attribute to an HTML element using JavaScript.

Below are the approaches used to add/update an attribute to an HTML element using JavaScript:

Approach 1: Using setAttribute() Method

It is used to add an attribute and provide it with a value to a specific element. If the attribute already exists, it just modifies or sets its value. 

Syntax: 

let elements = document.getElementById( "element_id" );
elements.setAttribute( "attribute", "value" );

Here we are initializing the element in JavaScript by getting its id and then using setAttribute() to modify its attribute.

Example: In this example, we are using setAttribute() Method.

html

<!DOCTYPE html>
<html lang="en">
 
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content=
        "width=device-width, initial-scale=1.0">
 
    <script>
        function modify() {
 
            // Update style attribute of element "heading"
            let heading = document.getElementById("heading");
            heading.setAttribute("style", "color:green");
 
            // Add style attribute to element "tagLine"
            let tagLine = document.getElementById("tagLine");
            tagLine.setAttribute("style", "color:blue");
        }
    </script>
</head>
 
<body>
    <h1 id="heading">
        GeeksforGeeks
    </h1>
 
    <p id="tagLine">- Society Of Geeks</p>
 
    <button onclick="modify()">
        Click to modify
    </button>
</body>
 
</html>

                    

Output: 

How to add/update an attribute to an HTML element using JavaScript?

How to add/update an attribute to an HTML element using JavaScript?

Approach 2: Using HTML DOM Attributes Property

We can modify HTML attributes by using HTML DOM Attributes property.

Syntax:

document.getElementById("element_id").attribute_name = attribute_value;

Example: In this example, we are using HTML DOM Attributes Property.

html

<!DOCTYPE html>
<html lang="en">
 
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content=
        "width=device-width, initial-scale=1.0">
 
    <script>
        function add() {
 
            // Get the values of fNum and sNum using getAttribute()
            const fNum = Number(document.getElementById("fNum").value);
            const sNum = Number(document.getElementById("sNum").value);
            const result = fNum + sNum;
 
            // Output the result in green colour
            const output = "Sum of two numbers is " + result;
            document.getElementById("result").style = "color:green";
            document.getElementById("result").innerHTML = output;
        }
    </script>
</head>
 
<body>
    <h1 style="color:green;">
        GeeksforGeeks
    </h1>
 
    <b>Enter first number :- </b>
    <input type="number" id="fNum">
    <br><br>
 
    <b>Enter second number :- </b>
    <input type="number" id="sNum">
    <br><br>
     
    <button onclick="add()">Add</button>
 
    <p id="result"></p>
</body>
 
</html>

                    

Output: 

How to add/update an attribute to an HTML element using JavaScript?

How to add/update an attribute to an HTML element using JavaScript?



Last Updated : 03 Jan, 2024
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