ParentNode.firstElementChild - Web APIs 编辑

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.
;(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);

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• NonDocumentTypeChildNode.nextElementSibling
• ParentNode.lastElementChild
• The ParentNode and ChildNode pure interfaces.
• Object types implementing this pure interface: Document, Element, and DocumentFragment.