The KeyboardEvent.altKey read-only property is a Boolean indicates if the alt key (Option or ⌥ on OS X) was pressed (true) or not (false) when the event occured.
var altKeyPressed = instanceOfKeyboardEvent.altKey
<html>
<head>
<title>altKey example</title>
<script type="text/javascript">
function showChar(e){
alert(
"Key Pressed: " + String.fromCharCode(e.charCode) + "\n"
+ "charCode: " + e.charCode + "\n"
+ "ALT key pressed: " + e.altKey + "\n"
);
}
</script>
</head>
<body onkeypress="showChar(event);">
<p>
Press any character key,
with or without holding down the ALT key.<br />
You can also use the SHIFT key together with the ALT key.
</p>
</body>
</html> | Specification | Status | Comment |
|---|---|---|
| Document Object Model (DOM) Level 3 Events Specification The definition of 'KeyboardEvent.altkey' in that specification. | Obsolete | Initial definition. |
| Feature | Edge | Firefox (Gecko) | Chrome | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
| Feature | Edge | Firefox Mobile (Gecko) | Android | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | (Yes) | ? | ? | ? | ? | ? |
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/altKey