Which unit has the difference of two Date.now() calls?

[espruino-discuss]

Posted at 2023-06-26 by @MaBecker

If you like to check the runtime of you code you can use something like this:

var t1, t2;
t1 = Date.now()
//begin code to messure
a = analogRead(D28);
// end code to messuere
t2 = Date.now()
print("runtime:", t2-t1);
/* output
runtime: 0.88500976562
*/

Are this 0.885 mili seconds or 0.885 micro second

Reference say:

Get the number of milliseconds elapsed since 1970 (or on embedded platforms, since startu)

So the difference should be micro seconds. Not shure because a output of Date.now() looks like this 41866529.26635742187.

[espruino-discuss]

Posted at 2023-06-26 by @fanoush

Reference say: "Get the number of milliseconds" So the difference should be micro seconds.

why milli-milli=micro?

Not shure because a output of Date.now() looks like this 41866529.26635742187.

Still it can be milli but with fraction

BTW there is also getTime() - similar but in seconds with fraction

EDIT: what is a bit strange is that in Bangle 2 emulator Date.now() has no fraction

[gfwilliams]

Posted at 2023-06-26 by @gfwilliams

what is a bit strange is that in Bangle 2 emulator Date.now() has no fraction

Yes... If I recall the JS spec says that Date.now() should be a whole number. But since we usually keep track of time to finer accuracy than that it felt like it would have been a mistake to deliberately throw away info just to make it look like desktop JS.

On the emulator Date.now() is only giving us time accurate to 1ms so that's all we give.

[espruino-discuss]

Posted at 2023-06-26 by @MaBecker

Ok, so it's 0.885 ms - Thanks