Function overloading in Javascript - Best practices

Question

What is the best way(s) to fake function overloading in Javascript?

I know it is not possible to overload functions in Javascript as in other languages. If I neede

Answer 1

While Default parameters is not overloading, it might solve some of the issues that developers face in this area. The input is strictly decided by the order, you can not re-order as you wish as in classical overloading:

function transformer(
    firstNumber = 1,
    secondNumber = new Date().getFullYear(),
    transform = function multiply(firstNumber, secondNumber) {
        return firstNumber * secondNumber;
    }
) {
    return transform(firstNumber, secondNumber);
}

console.info(transformer());
console.info(transformer(8));
console.info(transformer(2, 6));
console.info(transformer(undefined, 65));

function add(firstNumber, secondNumber) {
    return firstNumber + secondNumber;
}
console.info(transformer(undefined, undefined, add));
console.info(transformer(3, undefined, add));

Results in (for year 2020):

2020
16160
12
65
2021
2023

More info: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Default_parameters