overload the overloadedFunc() function

Question

I need to overload a function overloadedFunc() which takes 3 arguments. For the 1st argument of the function set the default value [1, 2, 3], for the 2nd - the value 2, for the 3rd - the function that returns the product of the first two arguments, and the function can multiply both arrays and numbers. The overloadedFunc() function returns the result of the default function. I have a code but it throws an error. How can I solve this problem?

function overloadedFunc(arg1 = [1, 2, 3], arg2 = 2, arg3 = multiply()) { const res = multiply(arg1, arg2); return res; } function multiply(arg1, arg2) { arg1.forEach((item) => { item * arg2; }); } console.log(overloadedFunc()); // [2, 4, 6] console.log(overloadedFunc([2, 4, 6], 3)); // [6, 12, 18] console.log(overloadedFunc(10)); // 20

What is the error? What line does it occur on? If you set a breakpoint on that line, what do you see? — Raymond Chen
– Raymond Chen, Commented Oct 24, 2022 at 15:03
in "Run code snippet" you can test my code. Error with forEach() — trainee
– trainee, Commented Oct 24, 2022 at 15:05
You are responsible for testing your code, not us. Set a breakpoint other, see why you cannot read the forEach property of undefined. Look at the stack trace to see why it is undefined. — Raymond Chen
– Raymond Chen, Commented Oct 24, 2022 at 15:05
You will get the same error again once you fix the arg3 issue when you call overloadedFunc(10), since 10 is a value (and therefor arg1 doesn't use the default), but does not have a .forEach() — DBS
– DBS, Commented Oct 24, 2022 at 15:10

Mr. Polywhirl · Accepted Answer · 2022-10-24 15:48:39Z

In overloadedFunc, you need to take multiply as a default (do not invoke the function); and you need to call arg3.

You can simplify the multiply function to return a mapping.

const multiply = (arr, n) => Array.isArray(arr) ? arr.map(x => x * n) : arr * n; const overloadedFunc = ( arg1 = [1, 2, 3], arg2 = 2, arg3 = multiply ) => arg3(arg1, arg2); console.log(overloadedFunc()); // [2, 4, 6] console.log(overloadedFunc([2, 4, 6], 3)); // [6, 12, 18] console.log(overloadedFunc(10)); // 20

.as-console-wrapper { top: 0; max-height: 100% !important; }

This can be re-written to simplify the arg3 (aka multiply) callback.

const multiply = (scalar, multiplier) => scalar * multiplier; const overloadedFunc = ( arg1 = [1, 2, 3], arg2 = 2, arg3 = multiply ) => Array.isArray(arg1) ? arg1.map(x => arg3(x, arg2)) : arg3(arg1, arg2); console.log(overloadedFunc()); // [2, 4, 6] console.log(overloadedFunc([2, 4, 6], 3)); // [6, 12, 18] console.log(overloadedFunc(10)); // 20

.as-console-wrapper { top: 0; max-height: 100% !important; }

Thanks for your reply. But I need to be able to pass a number like 10 to the overloadedFunc() function, and not like in your example in an array. Is it possible to implement like this?
@trainee ok, I updated the function to utilize a ternary to evaluate arg1 as an Array.

Mustafa Reda · Accepted Answer · 2022-10-24 15:16:02Z

look at the 3rd parameter, you are calling the function multiply() without any parameters, if you wanna send the reference use multiply

The code will be like this:

// fixing the 3rd parameter function overloadedFunc(arg1 = [1, 2, 3], arg2 = 2, arg3 = multiply) { const res = multiply(arg1, arg2); return res; }

// return the result in multiply function function multiply(arg1, arg2) { arg1.forEach((item) => { item * arg2; }); return arg1; }

// fix the 3rd call to use [10] in array instead of 10 as a number console.log(overloadedFunc()); // [2, 4, 6] console.log(overloadedFunc([2, 4, 6], 3)); // [6, 12, 18] console.log(overloadedFunc([10])); // [20]

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