The Node.firstChild read-only property returns the node's first child in the tree, or null if the node has no children.

If the node is a Document, it returns the first node in the list of its direct children.


var childNode = node.firstChild;


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>

  var p01 = document.getElementById('para-01');

In the above, the console 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 create a #text node, from a single space to multiple 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>

  var p01 = document.getElementById('para-01');

Now the console will show 'SPAN'.

To avoid the issue with node.firstChild returning #text or #comment nodes, Element.firstElementChild can be used to return only the first element node. However, node.firstElementChild requires a shim for Internet Explorer 9 and earlier.


DOM Standard (DOM)
# ref-for-dom-node-firstchild①

Browser compatibility

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