How to get timestamp and time difference in nodejs

There are many ways to get timestamps in Nodejs, for example:

1.new Date().getTime()

2.Date.now()

3.process.uptime()

4.process.hrtime()

If you usually want to get a timestamp, use these methods All are ok, so what’s the difference between these methods?

new Date().getTime() and Date.now()

These methods are based on the system time milliseconds of the node running environment, the effect of +new Date() writing method and new Date ().getTime() has the same effect.

In scenarios where timestamps are frequently used, you need to pay attention to method performance. Among these methods, Date.now() has the best performance and can be tested with a little code:

var t1 = new Date().getTime();
var t2 = t1;
var i = 0, count = 10000000, interval = 0;
 
for(i = 0; i < count; i++)
{
  t2 = new Date().getTime();
  interval = (t2 - t1);
}
interval = (t2 - t1);
console.log(&#39;【new Date().getTime()】interval: &#39;, interval);
 
t1 = new Date().getTime();
for(i = 0; i < count; i++)
{
  t2 = +new Date;
  interval = (t2 - t1);
}
interval = (t2 - t1);
console.log(&#39;【+new Date】interval: &#39;, interval);
 
t1 = new Date().getTime();
for(i = 0; i < count; i++)
{
  t2 = Date.now();
  interval = (t2 - t1);
}
interval = (t2 - t1);
console.log(&#39;【Date.now()】interval: &#39;, interval);

Output result:

[new Date().getTime()]interval: 1583

[+new Date]interval: 2189

[Date.now()]interval: 891

If you just get the timestamp, then using Date.now() is the best way, but if you want to calculate the time difference, these methods are There will be some problems: the system time of the running environment sometimes has a slight callback, so the time difference obtained is not accurate, and sometimes some BUGs will be caused.

process.hrtime()

This method is to obtain an accurate timestamp object based on an arbitrary past time point and the time from now: [seconds, nanoseconds]

> process.hrtime()
[ 3197146, 563552237 ]

This method has nothing to do with system time, so it will not be affected by system clock drift, and there will be no BUG when used to calculate the time difference.

But, there are always buts in everything - -

What if it is used in a place that is frequently called?

var t1 = new Date().getTime();
var t2 = t1;
var i = 0, count = 10000000, interval = 0;
 
var hrTime1 = process.hrtime();
var hrTime2 = hrTime1;
 
t1 = new Date().getTime();
for(i = 0; i < count; i++)
{
  hrTime2 = process.hrtime(hrTime1);
}
t2 = new Date().getTime();
interval = parseInt(hrTime2[0] * 1e3 + hrTime2[1] * 1e-6);
console.log(&#39;【hrTime】interval: &#39;, interval, t2 - t1);

[hrTime]interval: 6412 6413 If I remember correctly, the above Date.now() is about 900ms for the same number of creations!

process.hrtime() is too slow! ! !

It turns out that when nodejs handles high-precision time, the calculation is more complicated, takes up a lot of system resources, and is slow, so this method is not suitable for high-frequency applications. Please see below process.uptime()

process.uptime()

This function uses nodejs to start the running time to get a timestamp in seconds, accurate to milliseconds:

process.uptime

Input: 6.419

This function is based on the node startup time. It is also not affected by the system clock drift and is suitable for calculating time differences.

How is the performance of so many calls?

var t1 = new Date().getTime();
var t2 = t1;
var i = 0, count = 10000000, interval = 0;
 
t1 = process.uptime()*1000;
for(i = 0; i < count; i++)
{
  t2 = process.uptime()*1000;
  //interval = (t2 - t1);
}
interval = (t2 - t1);
console.log(&#39;【process.uptime()】interval: &#39;, interval);

Output: [process.uptime()]interval: 954

Compared with process.hrtime(), the performance is much better~

Don’t need to calculate so accurately, just be fast!

Then where you need to calculate the time difference at high frequency, it’s you!

The above is the entire content of nodejs for obtaining timestamp and time difference. I hope it will be helpful to everyone when using nodejs.

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