Tradução em progresso.
Retorna o elemento atualmente em foco, ou seja, o element que receberá os eventos do teclado caso o usuário digite algo. Esse attribute é somente-leitura.
Geralmente retorna um <input> ou <textarea>, caso esteja com uma seleção de texto ativa. Caso esteja, pode obter mais informações sobre a seleção utilizando as propriedades selectionStart e selectionEnd. Caso o elemento em foco seja um <select>(menu) ou <input> do tipo button, checkbox ou radio.
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> or null.
Syntax
var curElement = document.activeElement;
Example
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript" charset="utf-8">
function init() {
function onMouseUp(e) {
console.log(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 = selectedTextArea.id;
outputText.innerHTML = selection;
}
document.getElementById("ta-example-one").addEventListener("mouseup", onMouseUp, false);
document.getElementById("ta-example-two").addEventListener("mouseup", onMouseUp, false);
}
</script>
</head>
<body onload="init()">
<div>
Select some text from one of the Textareas below:
</div>
<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>
<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.
</textarea>
</form>
Active Element Id: <span id="output-element"></span><br/>
Selected Text: <span id="output-text"></span>
</body>
</html>
Notes
Originally introduced as a proprietary DOM extension in Internet Explorer 4, this property also is supported in Opera and Safari (as of version 4).
Specification
| Specification | Status | Comment |
|---|---|---|
| WHATWG HTML Living Standard The definition of 'activeElement' in that specification. |
Living Standard |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | 2 | 3.0 | 4 [1] | 9.6 | 4.0 |
| Feature | Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | ? | ? | ? | ? | ? |
[1]: IE9 suffers from a bug where trying to access the activeElement of an <iframe>'s window.parent Document (i.e. parent.document.activeElement) will throw an error.