Creating an Apps Script function that takes other functions as arguments - google-apps-script

Question

I want to create a function in APPSCRIPT that takes as argument another APPSCRIPT function.
I tried this:
function mainFunction(spreadsheetRange, secondaryFunction) {
// values = array of values retrieved from range
for (var i = 0; i < values.length; i = i+1) {
values[i] = secondaryFunction(values[i]);
}
// update the range with the new values
}
function function1() {
//something
}
function function2() {
//something
}
and running (after importing all these functions) in a google sheet cell the following formula:
=mainFunction(validrange, function2)
But this error appears:
TypeError: fun is not a function.
The same happens with=mainFunction(validrange, function2())
How can I solve this problem?

Answer 1

Although I'm not sure whether I could correctly understand your goal, the following modified script is your expected result?
Modified script:
function mainFunction(spreadsheetRange, secondaryFunction) {
// values = array of values retrieved from range
for (var i = 0; i < values.length; i = i+1) {
values[i] = this[secondaryFunction](values[i]); // <--- Modified
}
// update the range with the new values
}
In this modification, for example, when you put =mainFunction(validrange, "function2") to a cell, the function function2 is used with values[i] = this[secondaryFunction](values[i]).
But when I saw your function of function2, no arguments are used. So, in this case, values[i] is not given to function2. Please be careful about this.
In this case, please use "function2" of =mainFunction(validrange, "function2") as the text value. Please be careful about this.

Answer 2

I see no problem to pass a function as an argument:
function main() {
function mainFunction(func, arg) {
return func(arg);
}
function function1(num) { return num * 2 }
function function2(num) { return num * 3 }
var value = mainFunction(function1, 2);
console.log(value) // output ---> 4
var value = mainFunction(function2, 2);
console.log(value) // output ---> 6
}
You can try it right here:
function mainFunction(func, arg) {
return func(arg);
}
function function1(num) { return num * 2 }
function function2(num) { return num * 3 }
var value = mainFunction(function1, 2);
console.log(value) // output 4
var value = mainFunction(function2, 2);
console.log(value) // output 6