Arguments Optional passing only three out of five requirements

JavaScript
1

I am currently trying to solve Arguments Optional intermediate algorithm. I seem to pass the following requirements.

  1. addTogether(2, 3) should return 5.
  2. addTogether("http://bit.ly/IqT6zt") should return undefined.
  3. addTogether(2, "3") should return undefined.
    And these two do not pass.
  4. addTogether(2)(3) should return 5.
  5. addTogether(2)([3]) should return undefined.
function addTogether() {
let answer;
let myArgs = [].slice.call(arguments);
let val1 = arguments[0];
let val2 = arguments[1];
if(typeof val1 === 'number'&& typeof val2 === 'number'){
  answer = val1 + val2;
}else if(myArgs[val1] === 2){
 answer += val1[0] + val1[1]
}
return answer 
}

addTogether(2,3);

Thank you in advance for any help with this issue.

2

This is a tricky thing for many people to wrap their heads around for the first time, but what you need to do for those test cases is a function.

When addTogether() is called with only one parameter, it should return a function definition that expects only one parameter and returns the sum of that new parameter and the original parameter that addTogether() was called with.

3

I finally got all requirements to pass. Had to rewrite my code as follows.

function addTogether() {
let answer;
let arr = [].slice.call(arguments);
let test = arr.every(el => typeof el === 'number');//Test if argument passes being a number test by looping arguments and testing each one.
if(test){//If test is passed add arguments together.
  answer = arr[0] + arr[1];
}
 if(arr.length < 2){//If only one argument is found example (2) of (2)(3) then run addMe function.
   if(test){
  let addMe;
  addMe = (num2) => {
    if(typeof num2 === 'number'){//If num2 is a number then add first argument arr[0] with num2 which is 3.
    return arr[0] + num2
    }
    }
    answer = addMe;
   }
  }


return answer;
}

addTogether(2,3);

Hope i explained how i was trying to solve algorithm. Thank you ArielLeslie