The timeStamp
read-only property of the
Event
interface returns the time (in milliseconds) at which the event was
created.
Note: This property only works if the event system supports it for the particular event.
Syntax
time = event.timeStamp;
Value
This value is the number of milliseconds elapsed from the beginning of the current document's lifetime till the event was created.
In newer implementations, the value is a DOMHighResTimeStamp
accurate to
5 microseconds (0.005 ms). In older implementations, the value is a
DOMTimeStamp
, accurate to a millisecond.
Example
HTML
<p>
Focus this iframe and press any key to get the
current timestamp for the keypress event.
</p>
<p>timeStamp: <span id="time">-</span></p>
JavaScript
function getTime(event) {
var time = document.getElementById("time");
time.firstChild.nodeValue = event.timeStamp;
}
document.body.addEventListener("keypress", getTime);
Result
Reduced time precision
To offer protection against timing attacks and fingerprinting, the precision of
Event.timeStamp
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
event.timeStamp;
// 1519211809934
// 1519211810362
// 1519211811670
// ...
// reduced time precision with `privacy.resistFingerprinting` enabled
event.timeStamp;
// 1519129853500
// 1519129858900
// 1519129864400
// ...
In Firefox, if you also enable privacy.resistFingerprinting
, the precision
will be 100ms or the value of
privacy.resistFingerprinting.reduceTimerPrecision.microseconds
, whichever
is larger.
Specifications
Specification | Status | Comment |
---|---|---|
DOM The definition of 'Event.timeStamp' in that specification. |
Living Standard |
Browser compatibility
BCD tables only load in the browser