问题
How can I get a timestamp in JavaScript?
Something similar to Unix timestamp, that is, a single number that represents the current time and date. Either as a number or a string.
回答1:
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).
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());回答2:
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()
回答3:
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();
回答4:
var time = Date.now || function() {
return +new Date;
};
time();
回答5:
I provide multiple solutions with descriptions in this answer. Feel free to ask questions if anything is unclear
PS: sadly someone merged this to the top answer without giving credit.
Quick and dirty solution:
Date.now() /1000 |0
Warning: it might break in 2038 and return negative numbers if you do the
|0magic. UseMath.floor()instead by that time
Math.floor() solution:
Math.floor(Date.now() /1000);
Some nerdy alternative by Derek 朕會功夫 taken from the comments below this answer:
new Date/1e3|0
Polyfill to get Date.now() working:
To get it working in IE you could do this (Polyfill from MDN):
if (!Date.now) {
Date.now = function now() {
return new Date().getTime();
};
}
If you do not care about the year / day of week / daylight saving time you could strip it away and use this after 2038:
var now = (function () {
var year = new Date(new Date().getFullYear().toString()).getTime();
return function () {
return Date.now() - year
}
})();
Some output of how it will look:
new Date() Thu Oct 29 2015 08:46:30 GMT+0100 (Mitteleuropäische Zeit ) new Date(now()) Thu Oct 29 1970 09:46:30 GMT+0100 (Mitteleuropäische Zeit )Of course it will break daylight saving time but depending on what you are building this might be useful to you if you need to do binary operations on timestamps after int32 will break in 2038.
This will also return negative values but only if the user of that PC you are running your code on is changing their PC's clock at least to 31th of december of the previous year.
If you just want to know the relative time from the point of when the code was run through first you could use something like this:
var relativeTime = (function () {
var start = Date.now();
return function () {
return Date.now() - start
}
})();
In case you are using jQuery you could use $.now() as described in jQuery's Docs which makes the polyfill obsolete since $.now() internally does the same thing: (new Date).getTime()
If you are just happy about jQuery's version consider upvoting this answer since I did not find it myself.
Now a tiny explaination of what |0 does:
By providing |, you tell the interpreter to do a binary OR operation. Bit operations require absolute numbers which turns the decimal result from Date.now() / 1000 into an integer.
During that conversion, decimals are removed, resulting in the same result as using Math.floor() but using less code.
Be warned though: it will convert a 64 bit double to a 32 bit integer. This will result in information loss when dealing with huge numbers. Timestamps will break after 2038 due to 32 bit integer overflow.
For further information about Date.now follow this link: Date.now() @ MDN
回答6:
var timestamp = Number(new Date()); // current time as number
回答7:
jQuery provides its own method to get the timestamp:
var timestamp = $.now();
(besides it just implements (new Date).getTime() expression)
REF: http://api.jquery.com/jQuery.now/
回答8:
console.log(new Date().valueOf()); // returns the number of milliseconds since the epoch回答9:
Just to add up, here's a function to return a timestamp string in Javascript. Example: 15:06:38 PM
function displayTime() {
var str = "";
var currentTime = new Date()
var hours = currentTime.getHours()
var minutes = currentTime.getMinutes()
var seconds = currentTime.getSeconds()
if (minutes < 10) {
minutes = "0" + minutes
}
if (seconds < 10) {
seconds = "0" + seconds
}
str += hours + ":" + minutes + ":" + seconds + " ";
if(hours > 11){
str += "PM"
} else {
str += "AM"
}
return str;
}
回答10:
In addition to the other options, if you want a dateformat ISO, you get can get it directly
console.log(new Date().toISOString());回答11:
Date, a native object in JavaScript is the way we get all data about time.
Just be careful in JavaScript the timestamp depends on the client computer set, so it's not 100% accurate timestamp. To get the best result, you need to get the timestamp from the server-side.
Anyway, my preferred way is using vanilla. This is a common way of doing it in JavaScript:
Date.now(); //return 1495255666921
In MDN it's mentioned as below:
The Date.now() method returns the number of milliseconds elapsed since 1 January 1970 00:00:00 UTC.
Because now() is a static method of Date, you always use it as Date.now().
If you using a version below ES5, Date.now(); not works and you need to use:
new Date().getTime();
回答12:
One I haven't seen yet
Math.floor(Date.now() / 1000); // current time in seconds
Another one I haven't seen yet is
var _ = require('lodash'); // from here https://lodash.com/docs#now
_.now();
回答13:
The Date.getTime() method can be used with a little tweak:
The value returned by the getTime method is the number of milliseconds since 1 January 1970 00:00:00 UTC.
Divide the result by 1000 to get the Unix timestamp, floor if necessary:
(new Date).getTime() / 1000
The Date.valueOf() method is functionally equivalent to Date.getTime(), which makes it possible to use arithmetic operators on date object to achieve identical results. In my opinion, this approach affects readability.
回答14:
The code Math.floor(new Date().getTime() / 1000) can be shortened to new Date / 1E3 | 0.
Consider to skip direct getTime() invocation and use | 0 as a replacement for Math.floor() function.
It's also good to remember 1E3 is a shorter equivalent for 1000 (uppercase E is preferred than lowercase to indicate 1E3 as a constant).
As a result you get the following:
var ts = new Date / 1E3 | 0;
console.log(ts);回答15:
I highly recommend using moment.js. To get the number of milliseconds since UNIX epoch, do
moment().valueOf()
To get the number of seconds since UNIX epoch, do
moment().unix()
You can also convert times like so:
moment('2015-07-12 14:59:23', 'YYYY-MM-DD HH:mm:ss').valueOf()
I do that all the time. No pun intended.
To use moment.js in the browser:
<script src="moment.js"></script>
<script>
moment().valueOf();
</script>
For more details, including other ways of installing and using MomentJS, see their docs
回答16:
You can only use
var timestamp = new Date().getTime();
console.log(timestamp);to get the current timestamp. No need to do anything extra.
回答17:
Today - 2018.06.27 I provide some time comparison for pure js solutions. This can be useful for people who wanna get/measure time in JS in light/efficient way (eg. for real-time applications like simulations, games etc.)
Tested on MacOs High Sierra 10.13.3 on Chrome 67.0.3396.99 (64-bit), Safari 11.0.3 (13604.5.6), Firefox 59.0.2 (64-bit). On below screenshot I show you results for fastest browser (Safari):
As I observe the Date.now() was fastest method to get timestamp for all three browsers. Safari has 19.2M operations per second, Firefox 16.1M, Chrome 7.8M.
The new Date()*1 was slowest for Chrome (2.8M) and Firefox (2.6M). The Number(new Date()) was slowest for Safari (2.9M).
So the winner JS code is Date.now() and fastest browser is Safari (2x faster that chrome! ).
You can perform test on your machine here: https://jsperf.com/timestamp-test-x.
回答18:
Here is a simple function to generate timestamp in the format: mm/dd/yy hh:mi:ss
function getTimeStamp() {
var now = new Date();
return ((now.getMonth() + 1) + '/' +
(now.getDate()) + '/' +
now.getFullYear() + " " +
now.getHours() + ':' +
((now.getMinutes() < 10)
? ("0" + now.getMinutes())
: (now.getMinutes())) + ':' +
((now.getSeconds() < 10)
? ("0" + now.getSeconds())
: (now.getSeconds())));
}
回答19:
For a timestamp with microsecond resolution, there's performance.now:
function time() {
return performance.now() + performance.timing.navigationStart;
}
This could for example yield 1436140826653.139, while Date.now only gives 1436140826653.
回答20:
// The Current Unix Timestamp
// 1443534720 seconds since Jan 01 1970. (UTC)
// seconds
console.log(Math.floor(new Date().valueOf() / 1000)); // 1443534720
console.log(Math.floor(Date.now() / 1000)); // 1443534720
console.log(Math.floor(new Date().getTime() / 1000)); // 1443534720
// milliseconds
console.log(Math.floor(new Date().valueOf())); // 1443534720087
console.log(Math.floor(Date.now())); // 1443534720087
console.log(Math.floor(new Date().getTime())); // 1443534720087
// jQuery
// seconds
console.log(Math.floor($.now() / 1000)); // 1443534720
// milliseconds
console.log($.now()); // 1443534720087<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>回答21:
Any browsers not supported Date.now, you can use this for get current date time:
currentTime = Date.now() || +new Date()
回答22:
This one has a solution : which converts unixtime stamp to tim in js try this
var a = new Date(UNIX_timestamp*1000);
var hour = a.getUTCHours();
var min = a.getUTCMinutes();
var sec = a.getUTCSeconds();
回答23:
I learned a really cool way of converting a given Date object to a Unix timestamp from the source code of JQuery Cookie the other day.
Here's an example:
var date = new Date();
var timestamp = +date;
回答24:
If want a basic way to generate a timestamp in Node.js this works well.
var time = process.hrtime();
var timestamp = Math.round( time[ 0 ] * 1e3 + time[ 1 ] / 1e6 );
Our team is using this to bust cache in a localhost environment. The output is /dist/css/global.css?v=245521377 where 245521377 is the timestamp generated by hrtime().
Hopefully this helps, the methods above can work as well but I found this to be the simplest approach for our needs in Node.js.
回答25:
This seems to work.
console.log(clock.now);
// returns 1444356078076
console.log(clock.format(clock.now));
//returns 10/8/2015 21:02:16
console.log(clock.format(clock.now + clock.add(10, 'minutes')));
//returns 10/8/2015 21:08:18
var clock = {
now:Date.now(),
add:function (qty, units) {
switch(units.toLowerCase()) {
case 'weeks' : val = qty * 1000 * 60 * 60 * 24 * 7; break;
case 'days' : val = qty * 1000 * 60 * 60 * 24; break;
case 'hours' : val = qty * 1000 * 60 * 60; break;
case 'minutes' : val = qty * 1000 * 60; break;
case 'seconds' : val = qty * 1000; break;
default : val = undefined; break;
}
return val;
},
format:function (timestamp){
var date = new Date(timestamp);
var year = date.getFullYear();
var month = date.getMonth() + 1;
var day = date.getDate();
var hours = date.getHours();
var minutes = "0" + date.getMinutes();
var seconds = "0" + date.getSeconds();
// Will display time in xx/xx/xxxx 00:00:00 format
return formattedTime = month + '/' +
day + '/' +
year + ' ' +
hours + ':' +
minutes.substr(-2) +
':' + seconds.substr(-2);
}
};
回答26:
For lodash and underscore users, use _.now.
var timestamp = _.now(); // in milliseconds
回答27:
Moment.js can abstract away a lot of the pain in dealing with Javascript Dates.
See: http://momentjs.com/docs/#/displaying/unix-timestamp/
moment().unix();
回答28:
As of writing this, the top answer is 9 years old, and a lot has changed since then - not least, we have near universal support for a non-hacky solution:
Date.now()
If you want to be absolutely certain that this won't break in some ancient (pre ie9) browser, you can put it behind a check, like so:
const currentTimestamp = (!Date.now ? +new Date() : Date.now());
This will return the milliseconds since epoch time, of course, not seconds.
MDN Documentation on Date.now
回答29:
more simpler way:
var timeStamp=event.timestamp || new Date().getTime();
回答30:
sometime I need it in objects for xmlhttp calls, so I do like this.
timestamp : parseInt(new Date().getTime()/1000, 10)
来源：https://stackoverflow.com/questions/221294/how-do-you-get-a-timestamp-in-javascript