How to output numbers with leading zeros in JavaScript [duplicate]

Answer 1

From https://gist.github.com/1180489

function pad(a,b){return(1e15+a+"").slice(-b)}

With comments:

function pad(
  a, // the number to convert 
  b // number of resulting characters
){
  return (
    1e15 + a + // combine with large number
    "" // convert to string
  ).slice(-b) // cut leading "1"
}