underscore/lodash

lodash.padding.js

_.mixin((function() {
  function createPadding(value, pad, character) {
    character = _.isValue(character) ? String(character) : " ";

    var strPadded = "";
    var length = pad - value.length;

    while (strPadded.length < length && character.length) {
      strPadded += character;
    }
    return strPadded.slice(0, length);
  }

  return {
    isValue: function(value) {
      return !_.isNull(value) && !_.isUndefined(value);
    },
    
    padLeft: function(value, pad, character) {
      value = _.isValue(value) ? String(value) : "";
      return createPadding(value, pad, character) + value;
    },
    
    padRight: function(value, pad, character) {
      value = _.isValue(value) ? String(value) : "";
      return value + createPadding(value, pad, character);
    },
  };
})());