The type property of the OscillatorNode interface specifies what shape of waveform the oscillator will output. There are several common waveforms available, as well as an option to specify a custom waveform shape. The shape of the waveform will affect the tone that is produced.

A string specifying the shape of oscillator wave. The different available values are:

sine

A sine wave. This is the default value.

square

A square wave with a duty cycle of 0.5; that is, the signal is "high" for half of each period.

sawtooth

A sawtooth wave.

triangle

A triangle wave.

custom

A custom waveform. You never set type to custom manually; instead, use the setPeriodicWave() method to provide the data representing the waveform. Doing so automatically sets the type to custom.

InvalidStateError DOMException

Thrown if the value custom was specified. To set a custom waveform, just call setPeriodicWave(). Doing so automatically sets the type for you.

The following example shows basic usage of an AudioContext to create an oscillator node. For an applied example, check out our Violent Theremin demo (see app.js for relevant code).

// create web audio api context
const audioCtx = new (window.AudioContext || window.webkitAudioContext)();

// create Oscillator node
const oscillator = audioCtx.createOscillator();

oscillator.type = "square";
oscillator.frequency.setValueAtTime(440, audioCtx.currentTime); // value in hertz
oscillator.start();

• Using the Web Audio API