How to pass a range into a custom function in Google Spreadsheets? - function

Question

I am trying to compare two google sheets (for duplicate values) over a predefined range..
I am aware that google lets you compare sheets via tools, but i need a more customized comparison hence the function.
I want to create a function which takes in a range... something like:
function myFunction(range) {
var firstColumn = range.getColumn();
// loop over the range
}
The problem is that when I try doing this, the parameter seems like it is only passing the values to the function. Thus, I cannot use any of the Range methods such as getColumn(). When I attempt to do so, it gives the following error:
error: TypeError: Cannot find function getColumn in object 1,2,3.
How can I send an actual range rather than just the values to one of my custom functions?
Note- Range in my case is the entire sheet (both of them that need to be compared).
Thanks!

Answer 1

Custom functions arguments are calculated before being passed to the code of the custom function so range will be a single value or an array of values.
You could pass a reference to a range as a string, i.e. =myFunction("Sheet!A:Z"), then use something like the following:
function myFunction(reference) {
var range = SpreadsheetApp.getActiveSpreadsheet().getRangeByName(reference);
var firstColumn = range.getColumn();
// do something
}
Note: getRangeByName work both with named ranges and references os it could be a better choice than getRange.

Answer 2

Google Script treats ranges as Arrays. So, you could better work with entered range as you work with an array. Here's good technique how to loop through an array:
https://stackoverflow.com/a/14991272/5372400

Answer 3

In your cell, you would do
=myFunction("A1")
Then in your code
function myFunction(ref)
{
var range = SpreadsheetApp.getActiveSpreadsheet().getRangeByName(ref);
// do something with range
}
getRangeByName is no longer used.
Source: https://developers.google.com/apps-script/reference/spreadsheet/sheet#getrangea1notation