Node: firstChild property - Web APIs | MDN (original) (raw)
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 whitespacewill 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-firstchildâ‘ |