Please note, this is a STATIC archive of website developer.mozilla.org from 03 Nov 2016, cach3.com does not collect or store any user information, there is no "phishing" involved.

この記事はまだボランティアによって 日本語 に翻訳されていません。ぜひ MDN に参加して翻訳を手伝ってください!

The ParentNode.firstElementChild read-only property returns the object's first child Element, or null if there are no child elements.

This property was initially defined in the ElementTraversal pure interface. As this interface contained two distinct set of properties, one aimed at Node that have children, one at those that are children, they have been moved into two separate pure interfaces, ParentNode and ChildNode. In this case, firstElementChild moved to ParentNode. This is a fairly technical change that shouldn't affect compatibility.

Syntax

var childNode = elementNodeReference.firstElementChild; 

Example

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

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

In this example, the alert shows 'span', which is the tag name of the first child node of the paragraph element.

Polyfill for Internet Explorer 8

This property is unsupported prior to IE9, so the following snippet can be used to add support to IE8:

// Source: https://github.com/Alhadis/Snippets/blob/master/js/polyfills/IE8-child-elements.js
if(!("firstElementChild" in document.documentElement)){
    Object.defineProperty(Element.prototype, "firstElementChild", {
        get: function(){
            for(var nodes = this.children, n, i = 0, l = nodes.length; i < l; ++i)
                if(n = nodes[i], 1 === n.nodeType) return n;
            return null;
        }
    });
}

Specification

Specification Status Comment
DOM
The definition of 'ParentNode.firstElementChild' in that specification.
Living Standard Splitted the ElementTraversal interface in ChildNode and ParentNode. This method is now defined on the latter.
The Document and DocumentFragment implemented the new interfaces.
Element Traversal Specification
The definition of 'ElementTraversal.firstElementChild' in that specification.
Recommendation Added its initial definition to the ElementTraversal pure interface and use it on Element.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (on Element) 1.0 3.5 (1.9.1) 9.0 10.0 4.0
Support on Document and DocumentFragment 29.0 25.0 (25.0) Not supported 16.0 Not supported
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (on Element) (Yes) 1.0 (1.9.1) (Yes) (Yes) (Yes)
Support on Document and DocumentFragment (Yes) 25.0 (25.0) Not supported 16.0 Not supported

See also

ドキュメントのタグと貢献者

 最終更新者: Alhadis,