The keydown event is fired when a key is pressed.

Unlike the keypress event, the keydown event is fired for all keys, regardless of whether they produce a character value.

Bubbles Yes
Cancelable Yes
Interface KeyboardEvent
Event handler property onkeydown

The keydown and keyup events provide a code indicating which key is pressed, while keypress indicates which character was entered. For example, a lowercase "a" will be reported as 65 by keydown and keyup, but as 97 by keypress. An uppercase "A" is reported as 65 by all events.

Since Firefox 65, the keyup and keydown events are now fired during IME composition, to improve cross-browser compatibility for CJKT users (bug 354358, also see keydown and keyup events are now fired during IME composition for more useful details). To ignore all keydown events that are part of composition, do something like this (229 is a special value set for a keyCode relating to an event that has been processed by an IME):

eventTarget.addEventListener("keydown", event => {
  if (event.isComposing || event.keyCode === 229) {
    return;
  }
  // do something
});

Examples

This example logs the KeyboardEvent.code value whenever you press down a key inside the <input> element.

HTML

<input placeholder="Click here, then press down a key." size="40">
<p id="log"></p>

JavaScript

const input = document.querySelector('input');
const log = document.getElementById('log');

input.addEventListener('keydown', logKey);

function logKey(e) {
  log.textContent += ` ${e.code}`;
}

Result

Specifications

Specification Status
UI Events Working Draft

Browser compatibility

No compatibility data found. Please contribute data for "api.Document.keydown_event" (depth: 1) to the MDN compatibility data repository.

See also