BaseAudioContext: currentTime property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2021.
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
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 2ms. You can also enable privacy.resistFingerprinting, in which case the precision will be 100ms or the value of privacy.resistFingerprinting.reduceTimerPrecision.microseconds, whichever is larger.
For example, with reduced time precision, the result of audioCtx.currentTime will always be a multiple of 0.002, or a multiple of 0.1 (or privacy.resistFingerprinting.reduceTimerPrecision.microseconds) with privacy.resistFingerprinting enabled.
// reduced time precision (2ms) in Firefox 60
audioCtx.currentTime;
// Might be:
// 23.404
// 24.192
// 25.514
// …
// reduced time precision with `privacy.resistFingerprinting` enabled
audioCtx.currentTime;
// Might be:
// 49.8
// 50.6
// 51.7
// …
Specifications
| Specification |
|---|
| Web Audio API # dom-baseaudiocontext-currenttime |
Browser compatibility
| desktop | mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
currentTime
|
|
|
|
|
|
|
|
|
|
|
|
|
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support