Node: firstChild property
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.
html
<p id="para-01">
<span>First span</span>
</p>
<script>
const p01 = document.getElementById("para-01");
console.log(p01.firstChild.nodeName);
</script>
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.
html
<p id="para-01"><span>First span</span></p>
<script>
const p01 = document.getElementById("para-01");
console.log(p01.firstChild.nodeName);
</script>
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 Standard # ref-for-dom-node-firstchild① |
Browser compatibility
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