leftpad

leftpad.es5.js

function leftpad(str, length, char) {
  if (typeof str === "undefined") throw new Error("Cound't find string to leftpad")
  
  str = String(str)
  length = length || 0
  if (typeof char === "undefined") char = " "
  char = String(char)
  
  var padding = leftpad._repeat(char, Math.max(length - str.length, 0))
  return padding + str
}

leftpad._repeat = function(str, count) {
    return typeof str.repeat === "function" ? str.repeat(count) : new Array(count + 1).join(str)
}

Up for grabs!