Conditioning a Function (JS)

Question

I'm trying to return a message if one of the argument is not a number. Otherwise continue with the function. I'm trying this but it's not working as I'm expecting.. ..Please, any help?

function findingPairs(arr, value){
            if(isNaN(arr) || isNaN(value)){
                return "Please, introduce just numbers" 
            }
            let sum = 0;
            let finalOutput = [];
            for(let i = 0; i < arr.length; i++){
                    let numA = arr[i]
                    console.log(numA)
                } for(let j = 1; j < arr.length; j++){
                    let numB = arr[j]
                    console.log(numB)
                }
            }
        
       findingPairs([1,3,7], 9)

Answer 1

You can use Number.isInteger to check if something is a number. And Array.every over the array to check all the array.

Also I'm throwing an Error instead of returning a value because that's what is expected usually.

Error Docs

function findingPairs(arr, value) {
  if (!arr.every(Number.isInteger) || !Number.isInteger(value)) {
    throw new Error("Please, introduce just numbers");
  }

  let sum = 0;
  let finalOutput = [];

  for (let i = 0; i < arr.length; i++) {
    let numA = arr[i];
    console.log(numA);
  }
  for (let j = 1; j < arr.length; j++) {
    let numB = arr[j];
    console.log(numB);
  }
}

const value = findingPairs([1, 3, 7], 9);
const value2 = findingPairs([1, "a", 7], 9); // Will throw
const value2 = findingPairs([1, 23, 7], "hey"); // Will throw

console.log(value);

Answer 2

You need to check if each element of the array is a number, you can use Array.prototype.some() to test if one element of the array respects a condition

function findingPairs(arr, value){
    if(arr.some(isNaN) || isNaN(value)){
        return "Please, introduce just numbers" 
    }
    let sum = 0;
    let finalOutput = [];
    for(let i = 0; i < arr.length; i++){
            let numA = arr[i]
            console.log(numA)
    } 
    for(let j = 1; j < arr.length; j++){
            let numB = arr[j]
            console.log(numB)
    }
}

findingPairs([1,3,7], 9)