Default value of the cell of a Google Spreadsheet

Code.gs

function myFunction() {
  var value = SpreadsheetApp.openById("ABC").getSheets()[0].getRange("A1").getValue();
  Logger.log("value: %s"              , value              );
  Logger.log("value == '': %s"        , value ==  ""       );
  Logger.log("value === '': %s"       , value === ""       );
  Logger.log("value === undefined: %s", value === undefined);
  Logger.log("value === null: %s"     , value === null     );
  Logger.log("!value: %s"             , !value             );
  Logger.log("value === 0: %s"        , value === 0        );
}

/*
[18-02-27 18:36:33:868 MSK] value: 
[18-02-27 18:36:33:868 MSK] value == '': true
[18-02-27 18:36:33:869 MSK] value === '': true
[18-02-27 18:36:33:870 MSK] value === undefined: false
[18-02-27 18:36:33:870 MSK] value === null: false
[18-02-27 18:36:33:871 MSK] !value: true
[18-02-27 18:36:33:872 MSK] value === 0: false

[18-02-27 18:37:17:853 MSK] value: 0.0
[18-02-27 18:37:17:854 MSK] value == '': true
[18-02-27 18:37:17:854 MSK] value === '': false
[18-02-27 18:37:17:855 MSK] value === undefined: false
[18-02-27 18:37:17:855 MSK] value === null: false
[18-02-27 18:37:17:856 MSK] !value: true
[18-02-27 18:37:18:017 MSK] value === 0: true
*/