What do we call this type of argument passing mul(1)(2)(3) how to solve this and how to solve such scenario in case of n arguments passed like this

Question

What do we call this type of argument passing mul(1)(2)(3) how to solve this and how to solve such scenario in case of n arguments passed like this. I want to understand how this concept works.

Answer 1

It is called currying.

The main part is to return the same function again and again.

Then you need a mechanism to get the result. In Javascript, the toString method is called if the calling function requires a primitive value.

function mul(x) {
    function f(y) {            // the function to return
        x *= y;                // update the value
        return f;              // return the function
    };

    f.toString = function () { // overwrite toString prototype
       return x;               // return value
    };

    return f;                  // return function, enable currying
}

console.log(mul(1)(2)(3));
console.log(mul(1)(2)(3)(4)(5)(6));

Answer 2

This is called "currying" and is a short hand form for the result of a function call being another function that immediately gets invoked with another parameter.

First:

mul(1)

Is called and would return a function. Then that function would be called with the second argument:

resultingFunctionFromCallingmul(2)

Finally, that call would return yet another function that would be called with the final argument:

resultingFunctionFromCallingtheFirstResultingFunction(3)

Here's an example:

function a(input){
  console.log("function a called with " + input);
  return b;
}

function b(input){
  console.log("function b called with " + input);
  return c;
}

function c(input){
    console.log("function c called with " + input);
}

a("This is")(" a ")(" test.");