Using named ranged in google sheets as variables in custom formulas - google-apps-script

Question

Not sure if this is going to make sense but here I go.
What I want to do is to create a formula that isn't linked to a cell directly. In example: if I want to calculate carryweight for a tabletop game like D&D I would need the formula (strengthBonus x 5). For my current attempt I renamed the range (cell rather) strengthBonus to MOD_STR so when I put the formula =(multiply(MOD_STR,5) it works like a charm. Then I named that range "CARRYWEIGHT" and then use it elsewhere.
What I would like to be able to do is to make a new variable, similar to the way that "Define Named Range" does, but instead of relying on the variables being somewhere on the spreadsheet they would process from an internal formula. For example, if I type =carryweight into a cell it would run the equation =MULTIPLY(MOD_STR,5) in that cell and output the answer. I know nothing about code yet but have just been pointed in the direction of tutorials but I'm also asking for help here.
The code I have tried is
function CARRYWEIGHT(MOD_STR){
return MOD_STR*2}
and something else, I can't remember what but I got it to at least accept it in the spreadsheet. When I type it in I get an error stating that the outcome isn't a number.
I have no idea where to go from here.
Thank you in advanced for your help.

Answer 1

The difference between sheets formulas and Apps Script is that in Apps Script you need to retrieve the value of the range corresponding to the name of a named range
You cannot simply multiply the name of the range (which is a string!) with a number
Here is a sample of how to retrieve a range by name and make calculations wiht the value stored in it:
function CARRYWEIGHT(MOD_STR){
// retrieve all named ranges in the spreadsheet
var namedRanges = SpreadsheetApp.getActive().getNamedRanges();
//loop through all the results
for (var i = 0; i < namedRanges.length; i++){
var range = namedRanges[i];
//if the range with the name equal to the value of MOD_STR is found, get the cell content of this range
if(range.getName()==MOD_STR){
var value = range.getRange().getValue();
// perform the calculation with the cell content of the named range
return value*2;
}
}
}
From the cell, call the function as =CARRYWEIGHT("paste here the name of the range of interest"), do not forget the quotes (unless it is a cell reference)!
I hope this helped you to get started, for further understanding plese consult the following references.
References
Named Ranges
Loops
Conditional statements
Ranges
getValue()