Format JavaScript date as yyyy-mm-dd

Question

I have a date with the format Sun May 11,2014. How can I convert it to 2014-05-11 using JavaScript?

Answer 1

None of these answers quite satisfied me. I wanted a cross-platform solution that gave me the day in the local timezone without using any external libraries.

This is what I came up with:

function localDay(time) {
  var minutesOffset = time.getTimezoneOffset()
  var millisecondsOffset = minutesOffset*60*1000
  var local = new Date(time - millisecondsOffset)
  return local.toISOString().substr(0, 10)
}

That should return the day of the date, in YYYY-MM-DD format, in the timezone the date references.

So for example, localDay(new Date("2017-08-24T03:29:22.099Z")) will return "2017-08-23" even though it's already the 24th at UTC.

You'll need to polyfill Date.prototype.toISOString for it to work in Internet Explorer 8, but it should be supported everywhere else.