Write a “mul” function which will properly when invoked as below syntax

console.log(mul(2)(3)(4)); // output : 24
console.log(mul(4)(3)(4)); // output : 48

function mul (x) {
  return function (y) { // anonymous function
    return function (z) { // anonymous function
      return x * y * z;
    };
  };
}

Here mul function accept the first argument and return anonymous function which take the second parameter and return anonymous function which take the third parameter and return multiplication of arguments which is being passed in successive

In JavaScript function defined inside has access to outer function variable and function is the first class object so it can be returned by function as well and passed as argument in another function.

• A function is an instance of the Object type
• A function can have properties and has a link back to its constructor method
• Function can be stored as variable
• Function can be pass as a parameter to another function
• Function can be returned from function