一个关于 freeCodeCamp Challenge 的问题：Arguments Optional

Question

I'm stuck with one of curriculum in freeCodeCamp.org https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/arguments-optional

The below code is what I wrote. In that code, addTogether(2)(3) should be 5. But instead of that, addTogether(2)(3) is "undefined"

what's the problem?

I read all hints from freecodecamp forum. But I don't get it.

 function addTogether() { var checkNum = function(x) { if (typeof x === "number") { return x } else { return undefined } } if (arguments.length > 1) { if (checkNum(arguments[0]) !== undefined && checkNum(arguments[1]) !== undefined) { return arguments[0] + arguments[1] } else { return undefined } } else { var a = arguments[0] if (checkNum(a) === undefined) { return undefined } else { return function(args2) { args2 + a } } } return false; } console.log(addTogether(2)(3))

Answer 1

Your returned function doesn't have a return value. You could use

  return function(args2) {
     return args2 + a
  }

Or

  return (args2) => args2 + a

Answer 2

function addTogether(a,b) {

    
  
    if (arguments.length==2){
      if (typeof a == "number" && typeof b == "number"){
        return a + b;
      }
    }

    if(arguments.length==1){
      if (typeof a == "number"){
        return function(b){
          if (typeof b == "number"){
            return a + b;
          }
        };
      }
    }

}