KeyboardEvent: altKey property

Baseline

Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

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The KeyboardEvent.altKey read-only property is a boolean value that indicates if the alt key (Option or ⌥ on macOS) was pressed (true) or not (false) when the event occurred.

When the Alt key itself is pressed or released, this property is true for its keydown event and false for its keyup event, because both events fire after the state change.

Value

A boolean value.

Examples

html

<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>
<pre id="output"></pre>

const output = document.getElementById("output");

function showChar(e) {
  output.textContent = `Key KeyDown: "${e.key}"
ALT key KeyDown: ${e.altKey}
`;
}

document.addEventListener("keydown", showChar);