old_contents: module.exports = function(string) {
    return string.replace(/[^]/g, function(character) {
      // Escape all characters not included in SingleStringCharacters and
      // DoubleStringCharacters on
      // http://www.ecma-international.org/ecma-262/5.1/#sec-7.8.4
      switch (character) {
        case '"':
        case "'":
        case '\\':
          return '\\' + character
        // Four possible LineTerminator characters need to be escaped:
        case '\n':
          return '\\n'
        case '\r':
          return '\\r'
        case '\u2028':
          return '\\u2028'
        case '\u2029':
          return '\\u2029'
        default:
          return character
      }
    })
  }
  
new_contents: module.exports = function(string) {
    return string.replace(/["'\\\n\r\u2028\u2029]/g, function(character) {
      // Escape all characters not included in SingleStringCharacters and
      // DoubleStringCharacters on
      // http://www.ecma-international.org/ecma-262/5.1/#sec-7.8.4
      switch (character) {
        case '"':
        case "'":
        case '\\':
          return '\\' + character
        // Four possible LineTerminator characters need to be escaped:
        case '\n':
          return '\\n'
        case '\r':
          return '\\r'
        case '\u2028':
          return '\\u2028'
        case '\u2029':
          return '\\u2029'
      }
    })
  }
  
subject: Use much faster implementation