The KeyboardEvent altKey property in HTML DOM is a read-only property and used to return the boolean value which indicates the alt key is pressed or not. It returns True if alt key is pressed otherwise return false.
Syntax:
event.altKey
Below program illustrates the KeyboardEvent altkey property in HTML:
Example: This example check whether the “ALT” key is pressed or not.
html
<!DOCTYPE html><html>
<head>
<title>
HTML DOM KeyboardEvent altKey property
</title>
</head>
<body>
<h1>GeeksforGeeks</h1>
<h2>KeyboardEvent altKey Property</h2>
<p>
Check whether the alt key is pressed or not
</p>
<input type="text" onkeydown="keyboard(event)">
<p id = "test"></p>
<!-- script to check alt key event -->
<script>
function keyboard(event) {
var a = document.getElementById("test");
if (event.altKey) {
a.innerHTML = "The ALT key has been pressed!";
}
else {
a.innerHTML = "The ALT key has not been pressed!";
}
}
</script>
</body>
</html>
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Output:
Before Press the Key:
After Press the key:
Supported Browsers: The browser supported by KeyboardEvent altKey property are listed below:
- Opera 12.1
- Internet Explorer 9
- Google Chrome 1
- Edge 12
- Firefox 1.5
- Apple Safari 1.2