SourceBuffer: updatestart event

Limited availability

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

Note: This feature is available in Dedicated Web Workers.

The updatestart event of the SourceBuffer interface signals the beginning of an appendBuffer() or remove() operation. The updating attribute transitions from false to true.

Syntax

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

js
addEventListener("updatestart", (event) => { })

onupdatestart = (event) => { }

Event type

A generic Event.

Examples

Listening for the updatestart event

js
const sourceBuffer = source.addSourceBuffer(mimeCodec);
sourceBuffer.addEventListener("updatestart", () => {
  downloadStatus.textContent = "Modifying buffer...";
});
sourceBuffer.addEventListener("updateend", () => {
  downloadStatus.textContent = "Modification complete";
});

Specifications

Specification
Media Source Extensions™
# dfn-updatestart
Media Source Extensions™
# dom-sourcebuffer-onupdatestart

Browser compatibility

See also