HTML DOM TreeWalker firstChild() method

The TreeWalker firstChild() method moves the current Node to the first visible child of the current node, and returns the first found child.If no such child exists in the document, this method returns null.

Syntax:

node = treeWalker.firstChild();

Parameters: This method takes no parameters.

Return Value:

Returns firstChild of the node if exists.
Returns null if no such child exists.

Example: In this example, create a TreeWalker and hence showed the first child of the TreeWalker node.

html

<!doctype html>

<html>

<head>

    <meta charset="utf-8">

<title>HTML DOM TreeWalker firstChild() method</title>    

</head>

<body>

    <h1>GeeksforGeeks</h1>

    <p>Click Below</p>

    <button onclick="get()">Click</button>

</body>

<script>

        var treeWalker = document.createTreeWalker(

        document.body,

        NodeFilter.SHOW_ELEMENT,

        { acceptNode: function(node) {

 return NodeFilter.FILTER_ACCEPT; } },

        false
);

        function get(){

            var node = treeWalker.firstChild();

            console.log(node) 

        }

</script>

</html>