add.js

// This kata is all about adding numbers.

// You will create a function named add. It will return the sum of all the arguments.
// Sounds easy, doesn't it?

// Well Here's the Twist. The inputs will gradually decrease with their index as
// parameter to the function.

//   add(3,4,6);
//   /*
//   returns ( 3 / 1 ) + ( 4 / 2 ) + ( 6 / 3 ) = 7
//   */
// Remember the function will return 0 if no arguments are passed and it must round
// the result if sum is a float.

// Example

//   add(); //=> 0
//   add(1,2,3); //=> 3
//   add(1,4,-6,20); //=> 6

function add() {
  const args = Array.from(arguments);
  if (args.length == 0) {
    return 0;
  } else {
    return Math.round(
      args.map((el, idx) => el / [idx + 1]).reduce((a, b) => a + b)
    );
  }
}