Go time.Now().UnixNano() convert to milliseconds?
Solution 1:
The 2021 answer:
As of go v1.17, the time
package added UnixMicro()
and UnixMilli()
, so the correct answer would be: time.Now().UnixMilli()
Original answer:
Just divide it:
func makeTimestamp() int64 {
return time.Now().UnixNano() / int64(time.Millisecond)
}
Here is an example that you can compile and run to see the output
package main
import (
"time"
"fmt"
)
func main() {
a := makeTimestamp()
fmt.Printf("%d \n", a)
}
func makeTimestamp() int64 {
return time.Now().UnixNano() / int64(time.Millisecond)
}
Solution 2:
As @Jono points out in @OneOfOne's answer, the correct answer should take into account the duration of a nanosecond. Eg:
func makeTimestamp() int64 {
return time.Now().UnixNano() / (int64(time.Millisecond)/int64(time.Nanosecond))
}
OneOfOne's answer works because time.Nanosecond
happens to be 1
, and dividing by 1 has no effect. I don't know enough about go to know how likely this is to change in the future, but for the strictly correct answer I would use this function, not OneOfOne's answer. I doubt there is any performance disadvantage as the compiler should be able to optimize this perfectly well.
See https://en.wikipedia.org/wiki/Dimensional_analysis
Another way of looking at this is that both time.Now().UnixNano()
and time.Millisecond
use the same units (Nanoseconds). As long as that is true, OneOfOne's answer should work perfectly well.
Solution 3:
Keep it simple.
func NowAsUnixMilli() int64 {
return time.Now().UnixNano() / 1e6
}
Solution 4:
How can I get Unix time in Go in milliseconds?
Go 1.17 and above
No more divisions from nanoseconds. Starting from Go 1.17 you can just use Time.UnixMilli
method directly:
// a deterministic date value
t := time.Date(2021, 7, 16, 0, 0, 0, 0, time.UTC)
m := t.UnixMilli()
fmt.Println(m) // 1626393600000
Playground: https://play.golang.org/p/JSExv5jw2ZW
Solution 5:
At https://github.com/golang/go/issues/44196 randall77 suggested
time.Now().Sub(time.Unix(0,0)).Milliseconds()
which exploits the fact that Go's time.Duration
already have Milliseconds
method.