How do you get a timestamp in JavaScript? – Dev

The best answers to the question “How do you get a timestamp in JavaScript?” in the category Dev.

QUESTION:

Something similar to Unix’s timestamp, that is a single number that represents the current time and date. Either as a number or a string.

ANSWER:

I like this, because it is small:

+new Date

I also like this, because it is just as short and is compatible with modern browsers, and over 500 people voted that it is better:

Date.now()

ANSWER:

Short & Snazzy:

+ new Date()

A unary operator like plus triggers the valueOf method in the Date object and it returns the timestamp (without any alteration).

Details:

On almost all current browsers you can use Date.now() to get the UTC timestamp in milliseconds; a notable exception to this is IE8 and earlier (see compatibility table).

You can easily make a shim for this, though:

if (!Date.now) {
    Date.now = function() { return new Date().getTime(); }
}

To get the timestamp in seconds, you can use:

Math.floor(Date.now() / 1000)

Or alternatively you could use:

Date.now() / 1000 | 0

Which should be slightly faster, but also less readable.
(also see this answer or this with further explaination to bitwise operators).

I would recommend using Date.now() (with compatibility shim). It’s slightly better because it’s shorter & doesn’t create a new Date object. However, if you don’t want a shim & maximum compatibility, you could use the “old” method to get the timestamp in milliseconds:

new Date().getTime()

Which you can then convert to seconds like this:

Math.round(new Date().getTime()/1000)

And you can also use the valueOf method which we showed above:

new Date().valueOf()

Timestamp in Milliseconds

var timeStampInMs = window.performance && window.performance.now && window.performance.timing && window.performance.timing.navigationStart ? window.performance.now() + window.performance.timing.navigationStart : Date.now();

console.log(timeStampInMs, Date.now());

ANSWER:

var time = Date.now || function() {
  return +new Date;
};

time();

ANSWER:

JavaScript works with the number of milliseconds since the epoch whereas most other languages work with the seconds. You could work with milliseconds but as soon as you pass a value to say PHP, the PHP native functions will probably fail. So to be sure I always use the seconds, not milliseconds.

This will give you a Unix timestamp (in seconds):

var unix = Math.round(+new Date()/1000);

This will give you the milliseconds since the epoch (not Unix timestamp):

var milliseconds = new Date().getTime();