Returns the currently focused element, that is, the element that will get keystroke events if the user types any. This attribute is read only.

Often this will return an <input> or <textarea> object, if it has the text selection at the time.  If so, you can get more detail by using the element's selectionStart and selectionEnd properties.  Other times the focused element might be a <select> element (menu) or an <input> element, of type button, checkbox or radio.

注記: On Mac, elements that aren't text input elements tend not to get focus assigned to them.

Typically a user can press the tab key to move the focus around the page among focusable elements, and use the space bar to activate it (press a button, choose a radio).

Do not confuse focus with a selection over the document, consisting mostly of static text nodes.  See window.getSelection() for that.

When there is no selection, the active element is the page's <body>.

註: This attribute is part of the in-development HTML 5 specification.


var curElement = document.activeElement;

    <script type="text/javascript" charset="utf-8">
    function init() {

        function onMouseUp(e) {
            var outputElement = document.getElementById('output-element');
            var outputText = document.getElementById('output-text');
            var selectedTextArea = document.activeElement;
            var selection = selectedTextArea.value.substring(
            selectedTextArea.selectionStart, selectedTextArea.selectionEnd);
            outputElement.innerHTML =;
            outputText.innerHTML = selection;

        document.getElementById("ta-example-one").addEventListener("mouseup", onMouseUp, false);
        document.getElementById("ta-example-two").addEventListener("mouseup", onMouseUp, false);
<body onload="init()">
    Select some text from one of the Textareas below:
<form id="frm-example" action="#" accept-charset="utf-8">
<textarea name="ta-example-one" id="ta-example-one" rows="8" cols="40">
This is Textarea Example One: 
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec tincidunt, lorem a porttitor molestie, odio nibh iaculis libero, et accumsan nunc orci eu dui.
<textarea name="ta-example-two" id="ta-example-two" rows="8" cols="40">
This is Textarea Example Two:
Fusce ullamcorper, nisl ac porttitor adipiscing, urna orci egestas libero, ut accumsan orci lacus laoreet diam. Morbi sed euismod diam.
Active Element Id: <span id="output-element"></span><br/>
Selected Text: <span id="output-text"></span>


JSFiddle で確認


Originally introduced as a proprietary DOM extension in Internet Explorer 4, this property also is supported in Opera and Safari (as of version 4).



機能 Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
基本サポート 2 3.0 4 9.6 4.0
機能 Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
基本サポート ? ? ? ? ?



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