Super small relative dates

ago.js

module.exports = (function(){
  const MS =
    { seconds:                        1000
    , minutes:                   60 * 1000
    , hours:                60 * 60 * 1000
    , days:            24 * 60 * 60 * 1000
    , weeks:       7 * 24 * 60 * 60 * 1000
    , months: 30 * 7 * 24 * 60 * 60 * 1000
    , years:     365 * 24 * 60 * 60 * 1000 }

  return ago

  function ago ( origin ) {
    var delta = Date.now() - origin.getTime()
      , ago

    if ( ago = doDelta( 'years') )
      return ~~ago + 'y'
    else if ( ago = doDelta( 'months') )
      return ~~ago + 'm'
    else if ( ago = doDelta( 'weeks') )
      return ~~ago + 'w'
    else if ( ago = doDelta( 'days') )
      return ~~ago + 'd'
    else if ( ago = doDelta( 'hours') )
      return ~~ago + 'h'
    else if ( ago = doDelta( 'minutes') )
      return ~~ago + 'm'
    else if ( ago = doDelta( 'seconds') )
      return ~~ago + 's'

    return 'now'

    function doDelta ( type ) {
      var result = delta / MS[type]
      return result >= 1 && result
    }
  }

})()

example.js

var ago = require( './ago' )
  , now = new Date

console.log( ago( new Date( 2011, now.getMonth(), now.getDate(), now.getHours() - 5 ) ) ) // 5h

console.log( ago( new Date( 2011, now.getMonth(), now.getDate() - 15 ) ) ) // 2w

console.log( ago( new Date( 2006, now.getMonth(), now.getDate() ) ) ) // 5y

Nice!

Instead of new Date().getTime() (line 14), you could use Date.now().

So I can, thanks Mathias!