Node: firstChild property
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The read-only firstChild property of the Node interface
returns the node's first child in the tree,
or null if the node has no children.
If the node is a Document,
this property returns the first node in the list of its direct children.
Note:
This property returns any type of node that is the first child of this one.
It may be a Text or a Comment node.
If you want to get the first Element that is a child of another element,
consider using Element.firstElementChild.
Value
A Node, or null if there are none.
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>
const p01 = document.getElementById("para-01");
console.log(p01.firstChild.nodeName);
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>
const p01 = document.getElementById("para-01");
console.log(p01.firstChild.nodeName);
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.
Specifications
| Specification |
|---|
| DOM # ref-for-dom-node-firstchild① |