The read-only altKey property of the TouchEvent interface returns a boolean value indicating whether or not the alt (Alternate) key is enabled when the touch event is created. If the alt key is enabled, the attribute's value is true. Otherwise, it is false.

This property is Read only .

A boolean value that is true if the alt key is enabled for this event; and false if the alt is not enabled.

This example illustrates how to access the TouchEvent key modifier properties: TouchEvent.altKey, TouchEvent.ctrlKey, TouchEvent.metaKey and TouchEvent.shiftKey.

In following code snippet, the touchstart event handler logs the state of the event's modifier keys.

someElement.addEventListener(
  "touchstart",
  (e) => {
    // Log the state of this event's modifier keys
    console.log(`altKey = ${e.altKey}`);
    console.log(`ctrlKey = ${e.ctrlKey}`);
    console.log(`metaKey = ${e.metaKey}`);
    console.log(`shiftKey = ${e.shiftKey}`);
  },
  false,
);