Google-sheets – Google spreadsheet multiple auto-sorting

You can use the sort() function for that, but you have to have your data in one place, and an automatically sorted copy of that data in another place.

For example, say I have Sheet1 with my data:

   | A    | B    | C
=====================
 1 | This | this | 2
 2 | Is   | is   | 1
 3 | Test | test | 3

Then in Sheet2, cell A1, I would put this function:

=sort(Sheet1!A:C, 3, TRUE)

This would show my data, but sorted by column C (the third column), ascending.

   | A    | B    | C
=====================
 1 | Is   | is   | 1
 2 | This | this | 2
 3 | Test | test | 3

You need to rename your variable ss to sheet:

function onOpen(event) {
  var sheet = SpreadsheetApp.getActiveSpreadsheet();

  var columnToSortBy = 4;
  var tableRange = "A2:F99";

  var range = sheet.getRange(tableRange);
  range.sort( { column : columnToSortBy, ascending: false } );
}

If that does not work, try to use @w0lf's approach with the event argument:

var sheet = event.source.getActiveSheet();

UPDATE: To sort by several columns just put the sorting options into an array, like so:

range.sort( [4, 1] ); // or
range.sort( [{ column: 4, ascending: false }, 1] ); // or
range.sort( [{ column: 4, ascending: false }, { column: 1, ascending: false }] );

See the google dev docs for more details: https://developers.google.com/apps-script/class_range#sort .