LEFT OUTER JOIN 2 sheets using 1 column via Google App Script

Question

How to JOIN 2 tables on 1 column together like in SQL "LEFT OUTER JOIN" for a Google Sheet in a simple way using Google App Script?

Found solutions, but does not solves my issue:

• +200 lines of code that doesn't works - no proper documentation to get it working - https://stackoverflow.com/a/67149921/10270590
• Google sheets outer join & difference

Answer 1

Create a Google App Script that has embedded normal google sheet code.

  var sp = SpreadsheetApp.getActiveSheet();
  var col = [];
  for(var n=0 ; n < sp.getMaxRows(); n++){
    var hh = n + 1;
    col.push(['=VLOOKUP(A' + hh + ',sheet_to_look_up!A:C,2,false)']);
  }
  sp.getRange('L:L').setValues(col); 
  sp.getRange('L1').setValue('Column Header Name');