Give Google Apps Script Code Editor Hints for IntelliSense

Introduction

Editing code behind in your Google docs and spreadsheets, etc. does not interpret a variable type when it has its value set from a function call. This means you lose the benefits of the built in method name auto complete and so it's far too easy to introduce bugs. However, this is easily fixed.

The Problem

Consider the following source:

//
var myLib = (function () {
  // Internal Variables
  var _ss
  var DATA_SOURCE_ID = '1234567890123456789012345678901234567890ABCD'
  
  // Internal functions
  function getSS() {
    if (!_ss) {
      _ss = SpreadsheetApp.openById(DATA_SOURCE_ID)
    }
    return _ss
  } 

  // External methods
  function countTabs () {
    var ss = getSS()
    return ss.getSheets().length // NO INTELLISENSE ON ss
  }
})()

When you are writing the method countTabs and type the ".", you would expect to get a popup IntelliSense panel. However, nothing appears!

The problem is that the Apps Script editor is not able to infer that the call to getSS() always returns a Spreadsheet object.

The Fix

You can fix this problem using a comment.

Change the getSS method function to look like a simple variable assignment  in a comment like this:

  // Internal functions
  function getSS() {
    if (!_ss) {
      _ss = SpreadsheetApp.openById(DATA_SOURCE_ID)
    }
    return _ss
  } // getSS = SpreadsheetApp.getActive()

Then when you start wrinting code that has been assigned a value from the function, it will have the correct intellisense, almost as though you were using a typed language.

Hopefully, this will aid your productivity in Apps Script, especially if you are trying to write clean, DRY code, etc.

History

• 6^th May, 2020: Initial version