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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 element = node.firstElementChild; 

Example

<ul id="foo">
  <li>First  (1)</li>
  <li>Second (2)</li>
  <li>Third  (3)</li>
</ul>

<script>
var foo = document.getElementById('foo');
// yields: First  (1)
console.log(foo.firstElementChild.textContent);
</script>

Polyfill for IE8, IE9 and Safari

// Overwrites native 'firstElementChild' prototype.
// Adds Document & DocumentFragment support for IE9 & Safari.
// Returns array instead of HTMLCollection.
;(function(constructor) {
    if (constructor &&
        constructor.prototype &&
        constructor.prototype.firstElementChild == null) {
        Object.defineProperty(constructor.prototype, 'firstElementChild', {
            get: function() {
                var node, nodes = this.childNodes, i = 0;
                while (node = nodes[i++]) {
                    if (node.nodeType === 1) {
                        return node;
                    }
                }
                return null;
            }
        });
    }
})(window.Node || window.Element);

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.
Obsolete Added its initial definition to the ElementTraversal pure interface and use it on Element.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 ?3.59104
Support on Document and DocumentFragment29 ?25 No16 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes ?4 Yes Yes Yes
Support on Document and DocumentFragment Yes Yes ? ? ? No Yes

See also

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最終更新者: ExE-Boss,