EditContext: compositionstart event

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The compositionstart event of the EditContext interface fires when composition using a Input Method Editor (IME) window starts.

Syntax

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

js
addEventListener("compositionstart", (event) => {});

oncompositionstart = (event) => {};

Examples

Using compositionstart to change the editable region's border

In the following example, the editable region's border is set to red when the compositionstart event fires, and back to black when the compositionend event fires. Note that the event listener callbacks in this example are only called when using an IME window, or other platform-specific editing UI surfaces, to compose text.

css
#text-editor {
  border: 1px solid black;
}
#text-editor.is-composing {
  border-color: red;
}
html
<div id="text-editor"></div>
js
const editorElement = document.getElementById("text-editor");
const editContext = new EditContext();
editorElement.editContext = editContext;

editContext.addEventListener("compositionstart", (event) => {
  editorElement.classList.add("is-composing");
});

editContext.addEventListener("compositionend", (event) => {
  editorElement.classList.remove("is-composing");
});

Specifications

Specification
EditContext API
# dom-editcontext-oncompositionstart

Browser compatibility

BCD tables only load in the browser