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HTMLElement: beforeinput event

The DOM beforeinput event fires when the value of an <input>, 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.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js

addEventListener("beforeinput", (event) => {});

onbeforeinput = (event) => {};

Event type

Event properties

This interface inherits properties from its parents, UIEvent and Event.

InputEvent.data Read only

Returns a string with the inserted characters. This may be an empty string if the change doesn't insert text (for example, when deleting characters).

InputEvent.dataTransfer Read only

Returns a DataTransfer object containing information about richtext or plaintext data being added to or removed from editable content.

InputEvent.inputType Read only

Returns the type of change for editable content such as, for example, inserting, deleting, or formatting text.

InputEvent.isComposing Read only

Returns a Boolean value indicating if the event is fired after compositionstart and before compositionend.

Examples

Feature Detection

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

js

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

Simple logger

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

HTML

html

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

JavaScript

js

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

input.addEventListener("beforeinput", updateValue);

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

Result

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
beforeinput_event 60 79 87 No 47 10.1 60 60 87 44 10.3 8.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/beforeinput_event