HTMLElement: beforeinput event

The DOM beforeinput event fires when the value of an <input>, <select>, or <textarea> element is about to be modified. The event also applies to elements with contenteditable enabled, and to any element when designMode is turned on.

This allows web apps to override text edit behavior before the browser modifies the DOM tree, and provides more control over input events to improve performance.

In the case of contenteditable and designMode, the event target is the editing host. If these properties apply to multiple elements, the editing host is the nearest ancestor element whose parent isn't editable.

The following function returns true if beforeinput, and thus getTargetRanges, is supported.

function isBeforeInputEventAvailable() {
  return window.InputEvent && typeof InputEvent.prototype.getTargetRanges === "function";
}

This example logs the current value of the element, immediately before replacing that value with the new one applied to the <input> element.

HTML

<input placeholder="Enter some text" name="name"/>
<p id="values"></p>

JavaScript

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

input.addEventListener('beforeinput', updateValue);

function updateValue(e) {
  log.textContent = e.target.value;
}

Result

• Related event: input