How convert 2020-08-18T08:00:00 to miliseconds in javascript

Question

How can I convert this date format (2020-08-18T08:00:00), to milliseconds in javascript?

I'm using momentJS, but I haven't found how to do this conversion.

Thanks!!!

That date format doesn't contain digits that specify milliseconds. — Robert Harvey, Aug 17 '20 at 22:26
Perhaps you're looking for this? https://www.w3schools.com/jsref/jsref_gettime.asp — Robert Harvey, Aug 17 '20 at 22:27
Your input is lacking a timezone offset, so it cannot meaningfully/reliably be converted to milliseconds-past-the-epoch. — Niet the Dark Absol, Aug 17 '20 at 22:30
In moment.js you'd do `moment('2020-08-18T08:00:00').format('X')` or `moment('2020-08-18T08:00:00').unix()`, [RTFM](https://momentjs.com/docs/#/displaying/unix-timestamp-milliseconds/). — RobG, Aug 18 '20 at 03:09

Sascha · Answer 1 · 2020-08-18T03:34:43.197

0

You can create a new Date and use getTime(). Because of absence of timezone it's calculated on the users timezone and not UTC or serverside timezone.

Edited: Because different browser (e.g. Safari and Firefox) produce different results Why does Date.parse give incorrect results? I changed my code so is the date now generated by a secure method by programatical and not automatic parsing of the datestring.

In the old version I had: let date = new Date(dateStr); which works on the most browser but not on all as RobG mentioned.

let dateStr = '2020-08-18T08:00:00';

let parts = dateStr.split('T');
let datParts = parts[0].split('-');
let timeParts = parts[1].split(':');

let date = new Date(datParts[0], datParts[1]-1, datParts[2], timeParts[0], timeParts[1], timeParts[2]);

let ms = date.getTime()
console.log(ms);

edited Aug 18 '20 at 03:34

answered Aug 17 '20 at 22:41

Sascha

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Should work in theory, doesn't work in practice. E.g. Safari and Firefox produce different results. See [*Why does Date.parse give incorrect results?*](https://stackoverflow.com/questions/2587345/why-does-date-parse-give-incorrect-results) – RobG Aug 18 '20 at 03:05
@RobG - I changed it, so now it should work on all browsers. – Sascha Aug 18 '20 at 03:35
Yes, manual parse, consider `let [y, m, d, hr, min, sec] = dateStr.split(/\D/)`. :-) – RobG Aug 18 '20 at 22:13

score -1 · Answer 2 · answered Aug 17 '20 at 22:36

-1

You can pass that entire string to Date.parse() to get the milliseconds.

A caveat though: As others have pointed out, your date lacks a timezone so you'll be limited to the timezone in which the script is run.

const millis = Date.parse('2020-08-18T08:00:00');
console.log(millis);
console.log(new Date(millis));

answered Aug 17 '20 at 22:36

JVDL

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And parsing is inconsistent, Safari returns a different result to other browsers. – RobG Aug 18 '20 at 03:06
Yeah sure, because the time passed isn't accurate, so Safari will give the local time vs other implementations that provide UTC. – JVDL Aug 19 '20 at 06:59
That format is supposed to be parsed as local but Safari parses it as UTC. – RobG Aug 19 '20 at 08:36

How convert 2020-08-18T08:00:00 to miliseconds in javascript

2 Answers2