text: function sprintf() {
    //  discuss at: http://phpjs.org/functions/sprintf/
    // original by: Ash Searle (http://hexmen.com/blog/)
    // improved by: Michael White (http://getsprink.com)
    // improved by: Jack
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Dj
    // improved by: Allidylls
    //    input by: Paulo Freitas
    //    input by: Brett Zamir (http://brett-zamir.me)
    //   example 1: sprintf("%01.2f", 123.1);
    //   returns 1: 123.10
    //   example 2: sprintf("[%10s]", 'monkey');
    //   returns 2: '[    monkey]'
    //   example 3: sprintf("[%'#10s]", 'monkey');
    //   returns 3: '[####monkey]'
    //   example 4: sprintf("%d", 123456789012345);
    //   returns 4: '123456789012345'
    //   example 5: sprintf('%-03s', 'E');
    //   returns 5: 'E00'
  
    var regex = /%%|%(\d+\$)?([-+\'#0 ]*)(\*\d+\$|\*|\d+)?(\.(\*\d+\$|\*|\d+))?([scboxXuideEfFgG])/g;
    var a = arguments;
    var i = 0;
    var format = a[i++];
  
    // pad()
    var pad = function (str, len, chr, leftJustify) {
      if (!chr) {
        chr = ' ';
      }
      var padding = (str.length >= len) ? '' : new Array(1 + len - str.length >>> 0)
        .join(chr);
      return leftJustify ? str + padding : padding + str;
    };
  
    // justify()
    var justify = function (value, prefix, leftJustify, minWidth, zeroPad, customPadChar) {
      var diff = minWidth - value.length;
      if (diff > 0) {
        if (leftJustify || !zeroPad) {
          value = pad(value, minWidth, customPadChar, leftJustify);
        } else {
          value = value.slice(0, prefix.length) + pad('', diff, '0', true) + value.slice(prefix.length);
        }
      }
      return value;
    };
  
    // formatBaseX()
    var formatBaseX = function (value, base, prefix, leftJustify, minWidth, precision, zeroPad) {
      // Note: casts negative numbers to positive ones
      var number = value >>> 0;
      prefix = prefix && number && {
        '2': '0b',
        '8': '0',
        '16': '0x'
      }[base] || '';
      value = prefix + pad(number.toString(base), precision || 0, '0', false);
      return justify(value, prefix, leftJustify, minWidth, zeroPad);
    };
  
    // formatString()
    var formatString = function (value, leftJustify, minWidth, precision, zeroPad, customPadChar) {
      if (precision != null) {
        value = value.slice(0, precision);
      }
      return justify(value, '', leftJustify, minWidth, zeroPad, customPadChar);
    };
  
    // doFormat()
    var doFormat = function (substring, valueIndex, flags, minWidth, _, precision, type) {
      var number, prefix, method, textTransform, value;
  
      if (substring === '%%') {
        return '%';
      }
  
      // parse flags
      var leftJustify = false;
      var positivePrefix = '';
      var zeroPad = false;
      var prefixBaseX = false;
      var customPadChar = ' ';
      var flagsl = flags.length;
      for (var j = 0; flags && j < flagsl; j++) {
        switch (flags.charAt(j)) {
        case ' ':
          positivePrefix = ' ';
          break;
        case '+':
          positivePrefix = '+';
          break;
        case '-':
          leftJustify = true;
          break;
        case "'":
          customPadChar = flags.charAt(j + 1);
          break;
        case '0':
          zeroPad = true;
          customPadChar = '0';
          break;
        case '#':
          prefixBaseX = true;
          break;
        }
      }
  
      // parameters may be null, undefined, empty-string or real valued
      // we want to ignore null, undefined and empty-string values
      if (!minWidth) {
        minWidth = 0;
      } else if (minWidth === '*') {
        minWidth = +a[i++];
      } else if (minWidth.charAt(0) == '*') {
        minWidth = +a[minWidth.slice(1, -1)];
      } else {
        minWidth = +minWidth;
      }
  
      // Note: undocumented perl feature:
      if (minWidth < 0) {
        minWidth = -minWidth;
        leftJustify = true;
      }
  
      if (!isFinite(minWidth)) {
        throw new Error('sprintf: (minimum-)width must be finite');
      }
  
      if (!precision) {
        precision = 'fFeE'.indexOf(type) > -1 ? 6 : (type === 'd') ? 0 : undefined;
      } else if (precision === '*') {
        precision = +a[i++];
      } else if (precision.charAt(0) == '*') {
        precision = +a[precision.slice(1, -1)];
      } else {
        precision = +precision;
      }
  
      // grab value using valueIndex if required?
      value = valueIndex ? a[valueIndex.slice(0, -1)] : a[i++];
  
      switch (type) {
      case 's':
        return formatString(String(value), leftJustify, minWidth, precision, zeroPad, customPadChar);
      case 'c':
        return formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, zeroPad);
      case 'b':
        return formatBaseX(value, 2, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'o':
        return formatBaseX(value, 8, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'x':
        return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'X':
        return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad)
          .toUpperCase();
      case 'u':
        return formatBaseX(value, 10, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'i':
      case 'd':
        number = +value || 0;
        // Plain Math.round doesn't just truncate
        number = Math.round(number - number % 1);
        prefix = number < 0 ? '-' : positivePrefix;
        value = prefix + pad(String(Math.abs(number)), precision, '0', false);
        return justify(value, prefix, leftJustify, minWidth, zeroPad);
      case 'e':
      case 'E':
      case 'f': // Should handle locales (as per setlocale)
      case 'F':
      case 'g':
      case 'G':
        number = +value;
        prefix = number < 0 ? '-' : positivePrefix;
        method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(type.toLowerCase())];
        textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(type) % 2];
        value = prefix + Math.abs(number)[method](precision);
        return justify(value, prefix, leftJustify, minWidth, zeroPad)[textTransform]();
      default:
        return substring;
      }
    };
  
    return format.replace(regex, doFormat);
  }