code: function readWhitespace(text, offset, limit) {
                      while (offset < limit) {
                          var code = text.charCodeAt(offset);
                          switch (code) {
                              case 0x0009:    // tab
                              case 0x000B:    // vertical tab
                              case 0x000C:    // form feed
                              case 0x0020:    // space
                              case 0x00A0:    // no-breaking space
                              case 0xFEFF:    // BOM
                                  break;
  
                                  // There are no category Zs between 0x00A0 and 0x1680.
                                  //
                              case (code < 0x1680) && code:
                                  return offset;
  
                                  // Unicode category Zs
                                  //
                              case 0x1680:
                              case 0x180e:
                              case (code >= 0x2000 && code <= 0x200a) && code:
                              case 0x202f:
                              case 0x205f:
                              case 0x3000:
                                  break;
  
                              default:
                                  return offset;
                          }
                          offset++;
                      }
                      return offset;
                  }
docs: Hand-inlined isWhitespace.