BaseAudioContext.currentTime

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.

Syntax

var curTime = baseAudioContext.currentTime;

Example

var AudioContext = window.AudioContext || window.webkitAudioContext;
var 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.

// 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

Specification Status Comment
Web Audio API
The definition of 'currentTime' in that specification.
Working Draft Initial definition.

Browser compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
currentTimeChrome Full support 10
Prefixed
Full support 10
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Edge Full support ≤18Firefox Full support 53
Notes
Full support 53
Notes
Notes Originally implemented on AudioContext in Firefox 25.
IE No support NoOpera Full support 22
Full support 22
Full support 15
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Safari Full support 6
Prefixed
Full support 6
Prefixed
Prefixed Implemented with the vendor prefix: webkit
WebView Android Full support YesChrome Android Full support 33Firefox Android Full support 53
Notes
Full support 53
Notes
Notes Originally implemented on AudioContext in Firefox Android 26.
Opera Android Full support 22
Full support 22
Full support 14
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Safari iOS Full support 6
Prefixed
Full support 6
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Samsung Internet Android Full support 2.0

Legend

Full support
Full support
No support
No support
See implementation notes.
See implementation notes.
Requires a vendor prefix or different name for use.
Requires a vendor prefix or different name for use.

See also: