index.md

---

title: AudioScheduledSourceNode.start()
slug: Web/API/AudioScheduledSourceNode/start
page-type: web-api-instance-method
browser-compat: api.AudioScheduledSourceNode.start

---

{{APIRef("Web Audio API")}}

The start() method on {{domxref("AudioScheduledSourceNode")}} schedules a sound to begin playback at the specified time. If no time is specified, then the sound begins playing immediately.

Syntax

start()
start(when)

Parameters

• when {{optional_inline}}

  • : The time, in seconds, at which the sound should begin to play. This value is specified in the same time coordinate system as the {{domxref("AudioContext")}} is using for its {{domxref("BaseAudioContext/currentTime", "currentTime")}} attribute. A value of 0 (or omitting the when parameter entirely) causes the sound to start playback immediately.

Return value

None ({{jsxref("undefined")}}).

Exceptions

• InvalidStateNode {{domxref("DOMException")}}

  • : Thrown if the node has already been started. This error occurs even if the node is no longer running because of a prior call to {{domxref("AudioScheduledSourceNode.stop", "stop()")}}.

• {{jsxref("RangeError")}}

  • : Thrown if the value specified for when is negative.

Examples

This example demonstrates how to create an {{domxref("OscillatorNode")}} which is scheduled to start playing in 2 seconds and stop playing 1 second after that. The times are calculated by adding the desired number of seconds to the context's current time stamp returned by {{domxref("BaseAudioContext/currentTime", "AudioContext.currentTime")}}.

context = new AudioContext();
osc = context.createOscillator();
osc.connect(context.destination);

/* Schedule the start and stop times for the oscillator */

osc.start(context.currentTime + 2);
osc.stop(context.currentTime + 3);

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Using the Web Audio API

• {{domxref("AudioScheduledSourceNode.stop", "stop()")}}

• {{domxref("AudioScheduledSourceNode")}}

• {{domxref("AudioBufferSourceNode")}}

• {{domxref("ConstantSourceNode")}}

• {{domxref("OscillatorNode")}}