HTML DOM insertBefore() Method

The insertBefore() method in HTML DOM is used to insert a new node before the existing node as specified by the user.

Syntax:

node.insertBefore( newnode, existingnode )

Parameters: This method accepts two parameters as mentioned above and described below:

newnode: It is the required parameter. This parameter contains the new node object which need to insert.
existingnode: It is the required parameter. It describes the position where new node insert before this node. If it set to null then insertBefore method will insert the new node at the end.

Return Value: It returns the node object which represent the inserted node.

Example: In this example, insert a list element before the second node of the list.

html

<!DOCTYPE html>
<html>
  
<head>
    <title>
        HTML | DOM insertBefore() Method
  
    </title>
    <!--Script to insert a new node before existing node-->
    <script>
        function myGeeks() {
            var newItem = document.createElement("li");
            var textnode = document.createTextNode("Java");
            newItem.appendChild(textnode);
  
            var list = document.getElementById("subjects");
            list.insertBefore(newItem, list.childNodes[2]);
        }
    </script>
</head>
  
<body>
    <h1>
        Welcome To GeeksforGeeks
    </h1>
  
    <h2>
        HTML DOM insertBefore() Method
    </h2>
  
    <ul id="subjects">
        <li>C++</li>
        <li>Python</li>
    </ul>
  
    <p>
        Click on the button to insert an 
        element before Python
    </p>
  
    <button onclick="myGeeks()">
        Insert Node
    </button>
  
</body>
  
</html>