code: function findEscapeEnd(source, offset) {
      for (var i = 0; i < 7 && offset + i < source.length; i++) {
          var code = source.charCodeAt(offset + i);
  
          if (i !== 6 && isHex(code)) {
              continue;
          }
  
          if (i > 0) {
              offset += i - 1 + getNewlineLength(source, offset + i, code);
              if (code === SPACE || code === TAB) {
                  offset++;
              }
          }
  
          break;
      }
  
      return offset;
  }
docs: skip escaped unicode sequence that can ends with space [0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?