phpjs/workbench/strings/stripcslashes.js

php.js offers community built php functions in javascript

function stripcslashes(str) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: stripcslashes("\\f\\o\\o\\[ \\]");
  // *     returns 1: 'foo[ ]'

  var target = '', i = 0, sl = 0, s = '', next = '', hex = '', oct = '', hex2DigMax = /[\dA-Fa-f]{1,2}/, rest = '', seq = '',
      oct3DigMaxs = /([0-7]{1,3})((\\[0-7]{1,3})*)/, oct3DigMax = /(\\([0-7]{1,3}))*/g, escOctGrp = [];

  for (i = 0, sl = str.length; i < sl; i++) {
    s = str.charAt(i);
    next = str.charAt(i + 1);
    if (s !== '\\' || !next) {
      target += s;
      continue;
    }
    switch (next) {
      case 'r': target += '\u000D'; break;
      case 'a': target += '\u0007'; break;
      case 'n': target += '\n'; break;
      case 't': target += '\t'; break;
      case 'v': target += '\v'; break;
      case 'b': target += '\b'; break;
      case 'f': target += '\f'; break;
      case '\\': target += '\\'; break;
      case 'x': // Hex (not used in addcslashes)
        rest = str.slice(i + 2);
        if (rest.search(hex2DigMax) !== -1) { // C accepts hex larger than 2 digits (per http://www.php.net/manual/en/function.stripcslashes.php#34041 ), but not PHP
          hex = (hex2DigMax).exec(rest);
          i += hex.length; // Skip over hex
          target += String.fromCharCode(parseInt(hex, 16));
          break;
        }
      // Fall-through
      default: // Up to 3 digit octal in PHP, but we may have created a larger one in addcslashes
        rest = str.slice(i + 2);
        if (rest.search(oct3DigMaxs) !== -1) { // C accepts hex larger than 2 digits (per http://www.php.net/manual/en/function.stripcslashes.php#34041 ), but not PHP
          oct = (oct3DigMaxs).exec(rest);
          i += oct[1].length; // Skip over first octal
          // target += String.fromCharCode(parseInt(oct[1], 8)); // Sufficient for UTF-16 treatment

          // Interpret int here as UTF-8 octet(s) instead, produce non-character if none
          rest = str.slice(i + 2); // Get remainder after the octal (still need to add 2, since before close of iterating loop)
          seq = '';

          if ((escOctGrp = oct3DigMax.exec(rest)) !== null) {
            seq += '%' + parseInt(escOctGrp[2], 8).toString(16);
          }
          /* infinite loop
                    while ((escOctGrp = oct3DigMax.exec(rest)) !== null) {
                        seq += '%'+parseInt(escOctGrp[2], 8).toString(16);
                    }

                    dl('stripcslashes');
                    alert(
                        stripcslashes('\\343\\220\\201')
                    )
                    */

          try {
            target += decodeURIComponent(seq);
          }
          catch (e) { // Bad octal group
            target += '\uFFFD'; // non-character
          }

          break;
        }
        target += next;
        break;
    }
    ++i; // Skip special character "next" in switch
  }
}