I found this article and tried the tutorial. Basically, you can use the date constructor to parse a date, then write get the seconds from the getTime() method

var d=new Date("October 13, 1975 11:13:00");
document.write(d.getTime() + " milliseconds since 1970/01/01");

Does this work?

There is not. The closest built-in option is Date.parse(), which parses a very limited subset of what strtotime() can:

var ts = Date.parse("2010-10-29");

It's worth noting that this function returns milliseconds instead of seconds, so you need to divide the result by 1000 to get an equivalent value to PHP's function.

Check out this implementation of PHP's strtotime() in JavaScript!

I found that it works identically to PHP for everything that I threw at it.

Update: this function as per version 1.0.2 can't handle this case: '2007:07:20 20:52:45' (Note the : separator for year and month)

Update 2018:

This is now available as an npm module! Simply npm install locutus and then in your source:

var strtotime = require('locutus/php/datetime/strtotime');

I jealous the strtotime() in php, but I do mine in javascript using moment. Not as sweet as that from php, but does the trick neatly too.

// first day of the month
var firstDayThisMonth = moment(firstDayThisMonth).startOf('month').toDate();

Go back and forth using the subtract() and add() with the endOf() and startOf():

// last day of previous month
var yesterMonthLastDay = moment(yesterMonthLastDay).subtract(1,'months').endOf('month').toDate();

Browser support for parsing strings is inconsistent. Because there is no specification on which formats should be supported, what works in some browsers will not work in other browsers.

Try Moment.js - it provides cross-browser functionality for parsing dates:

var timestamp = moment("2013-02-08 09:30:26.123");
console.log(timestamp.milliseconds()); // return timestamp in milliseconds
console.log(timestamp.second()); // return timestamp in seconds

There are few modules that provides similar behavior, but not exactly like PHP's strtotime. Among few alternatives I found date-util yields the best results.

Maybe you can exploit a sample function like :

function strtotime(date, addTime){
let generatedTime=date.getTime();
if(addTime.seconds) generatedTime+=1000*addTime.seconds; //check for additional seconds
if(addTime.minutes) generatedTime+=1000*60*addTime.minutes;//check for additional minutes
if(addTime.hours) generatedTime+=1000*60*60*addTime.hours;//check for additional hours
return new Date(generatedTime);
}


let futureDate = strtotime(new Date(), {
hours: 1, //Adding one hour
minutes: 45 //Adding fourty five minutes
});
document.body.innerHTML = futureDate;

`

For those looking to convert the datetime to unix timestamp, you can do this using the Moment Library.

For Vue.js, you can do something like

let start = "2022/02/02 02:02:02";
return moment(start).format("x");