strftime.js

// ex: strftime("%Y-%m-%d %H:%M:%S")
function strftime(format, d) {
  d = d || new Date()
  function pad (v) { return ("0" + v).substr(-2, 2) }
  var r = format.replace(/%Y/g, d.getFullYear())
  r = r.replace(/%m/g, pad(d.getMonth() + 1))
  r = r.replace(/%d/g, pad(d.getDate()))
  r = r.replace(/%H/g, pad(d.getHours()))
  r = r.replace(/%M/g, pad(d.getMinutes()))
  r = r.replace(/%S/g, pad(d.getSeconds()))
  return r
}