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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.
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) No support 16.0 No support
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) No support 16.0 No support

See also

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 最終更新者: k-gun,