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

When ES2018 rolls around (works in chrome) you can simply regex it

(new Date())
    .toISOString()
    .replace(
        /^(?\d+)-(?\d+)-(?\d+)T.*$/,
        '$-$-$'
    )

2020-07-14

Or if you'd like something pretty versatile with no libraries whatsoever

(new Date())
    .toISOString()
    .match(
        /^(?\d\d(?\d\d))-(?0?(?\d+))-(?
0?(?\d+))T(?0?(?\d+)):(?0?(?\d+)):(?(?0?(?\d+))\.\d+)(?[A-Z][\dA-Z.-:]*)$/
    )
    .groups

Which results in extracting the following

{
    H: "8"
    HH: "08"
    M: "45"
    MM: "45"
    S: "42"
    SS: "42"
    SSS: "42.855"
    d: "14"
    dd: "14"
    m: "7"
    mm: "07"
    timezone: "Z"
    yy: "20"
    yyyy: "2020"
}

Which you can use like so with replace(..., '$/$/\'$ @ $:$') as at the top instead of .match(...).groups to get

14/7/'20 @ 8:45