HTML DOM getElementById() Method

Last Updated : 02 Sep, 2024

The getElementById() method returns the elements that have given an ID which is passed to the function. This function is a widely used HTML DOM method in web designing to change the value of any particular element or get a particular element. If the passed ID to the function does not exist then it returns null.

Note: Each ID needs to be unique. If there are multiple elements with the same ID, only the first one will be returned.

Syntax:

document.getElementById( element_ID )

Parameter:

This function accepts single parameter element_ID which is used to hold the ID of the element.

Return Value:

It returns the object of the given ID. If no element exists with the given ID then it returns null.

Example 1: This example describes the getElementById() method where element_id is used to change the color of the text on clicking the button.

HTML

<!DOCTYPE html>
<html>

<head>
    <title>
        DOM getElementById() Method
    </title>
    <script>
        // Function to change the color of element
        function geeks() {
            let demo = document.getElementById("geeks");
            demo.style.color = "green";
        }
    </script>
</head>

<body style="text-align:center">
    <h1 id="geeks">GeeksforGeeks</h1>
    <h2>DOM getElementById() Method</h2>

    <!-- Click on the button to change color -->
    <input type="button" onclick="geeks()" 
           value="Click here to change color" />
</body>

</html>

Output:

Example 2: This example describes the getElementById() method where the element_id is used to change the content on clicking the button.

HTML

<!DOCTYPE html>
<html>

<head>
    <title>
        DOM getElementById() Method
    </title>
    <script>

        // Function to change content of element
        function geeks() {
            let demo = document.getElementById("geeks");
            demo.innerHTML = "Welcome to GeeksforGeeks!";
        }
    </script>
</head>

<body style="text-align:center">
    <h1>GeeksforGeeks</h1>
    <h2>DOM getElementById() Method</h2>
    <h3 id="geeks">Hello Geeks!</h3>

    <!-- Click here to change content -->
    <input type="button" 
           onclick="geeks()" 
           value="Click here to change content" />
</body>

</html>