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BaseAudioContext: currentTime property

The currentTime read-only property of the BaseAudioContext interface returns a double representing an ever-increasing hardware timestamp in seconds that can be used for scheduling audio playback, visualizing timelines, etc. It starts at 0.

Value

A floating point number.

Examples

js

const audioCtx = new AudioContext();
// Older webkit/blink browsers require a prefix

// …

console.log(audioCtx.currentTime);

Reduced time precision

To offer protection against timing attacks and fingerprinting, the precision of audioCtx.currentTime might get rounded depending on browser settings. In Firefox, the privacy.reduceTimerPrecision preference is enabled by default and defaults to 20us in Firefox 59; in 60 it will be 2ms.

js

// reduced time precision (2ms) in Firefox 60
audioCtx.currentTime;
// 23.404
// 24.192
// 25.514
// …

// reduced time precision with `privacy.resistFingerprinting` enabled
audioCtx.currentTime;
// 49.8
// 50.6
// 51.7
// …

In Firefox, you can also enabled privacy.resistFingerprinting, the precision will be 100ms or the value of privacy.resistFingerprinting.reduceTimerPrecision.microseconds, whichever is larger.

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
currentTime 14 12 25 No 15 6 4.4.3 18 25 14 6 1.0

See also

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https://developer.mozilla.org/en-US/docs/Web/API/BaseAudioContext/currentTime