Node.firstChild

The Node.firstChild read-only property returns the node's first child in the tree, or null if the node is childless. If the node is a Document, it returns the first node in the list of its direct children.

Syntax

var childNode = node.firstChild;

Example

This example demonstrates the use of firstChild and how whitespace nodes might interfere with using this property.

<p id="para-01">
  <span>First span</span>
</p>

<script type="text/javascript">
  var p01 = document.getElementById('para-01');
  console.log(p01.firstChild.nodeName);
</script>

In the above, the alert will show '#text' because a text node is inserted to maintain the whitespace between the end of the opening <p> and <span> tags. Any whitespace will cause the #text node to be inserted, from a single space to any number of spaces, returns, tabs, and so on.

Another #text node is inserted between the closing </span> and </p>tags.

If this whitespace is removed from the source, the #text nodes are not inserted and the span element becomes the paragraph's first child.

<p id="para-01"><span>First span</span></p>

<script type="text/javascript">
  var p01 = document.getElementById('para-01');
  console.log(p01.firstChild.nodeName);
</script>

Now the alert will show 'SPAN'.

To avoid the issue with #text or #comment nodes being returned by node.firstChild, ParentNode.firstElementChild can be used to return only the first element node. The caveat being that ParentNode.firstElementChild requires a shim for IE8, IE9 and Safari. 

Specifications

Browser compatibility