How to convert Date format like this Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time) to 2020-04-20T00:00:00.000Z in Javascript?

Question

I have a Date format like this "Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)"

I want to convert that above format to this format 2020-04-20T00:00:00.000Z

Actually I tried this JSON.stringify(new Date("Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)")) while using this am getting the output one day before 2020-04-19T18:30:00.000Z

so please anyone help me to convert this date format "Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)" like this 2020-04-20T00:00:00.000Z

Thanks in Advance.

Answer 1

Your date seems to be a standard string representation of new Date(), you can get the desired format by using new Date().toISOString()

console.log(new Date().toString())
console.log(new Date().toISOString())

// To create it from string
let dateStr = "Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)"
console.log(new Date(dateStr).toISOString())

Answer 2

Anurag Srivastava's answer shows how you should parse the string and format it in the required format (given that the string is in one of the two formats supported by ECMA-262 and considering Why does Date.parse give incorrect results?).

Note that "Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)" is the same instant in time as "2020-04-19T18:30:00.000Z". The first string is offset from UTC by 5 hr 30 min, so the equivalent UTC time is 5 hr 30 min earlier, which means the date is the previous day.

You haven't given a reason why you want to treat it as UTC and not consider the offset, so I don't think you should.

However, if you do have a good reason to parse it as UTC and ignore the supplied offset, then you can either:

1. Modify the input string to set the offset as +0 and parse it using the built–in parser
2. Parse the string yourself and treat it as UTC

let s = "Fri Apr 20 2020 00:00:00 GMT+0530 (India Standard Time)";

// #1 Modify the input string, setting the offset to +0
let d = new Date(s.replace(/GMT.*$/,'GMT+0000')).toISOString();

console.log(d.toISOString());

// #2 Bespoke parser
function parseAsUTC(s) {
  let months = ['jan','feb','mar','apr','may','jun',
                'jul','aug','sep','oct','nov','dec'];
  let b = s.split(/\W/);
  return new Date(Date.UTC(b[3], months.indexOf(b[1].toLowerCase()),
                           b[2], b[4], b[5], b[6]));
}

console.log(parseAsUTC(s).toISOString());