Why does a date length return Null?-CodePudding

I have an array variable that get the values of a spreadsheet

I want to check if some of the cells are empty, so I look the length of each element of the array

But to my surprise, if the element is a date, the length returns "null". Shouldn't it return the full length of the date ? (e.g. Wed Dec 01 03:00:00 GMT-05:00 2021 should return 34)

Can someone explain this behaviour to me ?

Here is the code I use:

In my table the cell I1 is a date and the cell J1 is empty

var sheet = SpreadsheetApp.getActive().getSheetByName('Example');
    
var tab = sheet.getRange(1, 1, sheet.getLastRow(), sheet.getLastColumn()).getValues();

Logger.log(tab[0][8]);
Logger.log(tab[0][8].length);
Logger.log(tab[0][9]);
Logger.log(tab[0][9].length);

This return:

1:28:09 PM  Notice  Execution started
1:28:15 PM  Info    Wed Dec 01 03:00:00 GMT-05:00 2021
1:28:17 PM  Info    null
1:28:18 PM  Info    
1:28:19 PM  Info    0.0

CodePudding user response：

Only Google Apps Script product engineers could answer why, but based on the https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date length is not a property of the Date object.

When using Logger.log or console.log to print any object to the IDE executions log, they will try to convert that object into a string according to the rules set to do that but Google Apps Script documentation doesn't provide details of what will be displayed when non string is passed. As you can see in the bottom each method have different results.

JSON.stringify and Utilities.formatDate methods for formatting Date object as strings, works with the old and the new runtime. When using the default runtime (V8) you might also might other Date properties like Date.prototype.toDateString among others.

Please bear in mind that Date.prototype.toLocaleString will consider as the local of the server, not from the user computer.

function myFunction() {
  const date = new Date();
  Logger.log(date);
  Logger.log(date.length);
  console.log(date);
  console.log(date.length);

}

10:39:27 AM Notice  Execution started
10:39:27 AM Info    Thu Mar 03 11:39:27 GMT-05:00 2022
10:39:27 AM Info    null
10:39:27 AM Info    Thu Mar 03 2022 11:39:27 GMT-0500 (Eastern Standard Time)
10:39:27 AM Info    undefined
10:39:27 AM Notice  Execution completed

References

CodePudding user response：

Based on the comments we can edit the code and use both alternatives to convert the string and avoid the null.

var sheet = SpreadsheetApp.getActive().getSheetByName("Sheet1");
    
    
//var tab = sheet.getRange(1, 1, sheet.getLastRow()-1, sheet.getLastColumn()-1).getValues();

var tab = sheet.getRange(1, 1, sheet.getLastRow(), sheet.getLastColumn()).getDisplayValues();

var date = new Date(tab[0][8]);

var date2 = date.toString();

Logger.log(tab[0][8]);
Logger.log(tab[0][8].length);
Logger.log(tab[0][9]);
Logger.log(tab[0][9].length);

Logger.log(date2.length)