Freecodecamp challenge

splice.js

function frankenSplice(arr1, arr2, n) {
let arr3 = [];
   arr2.splice(n, 0, arr1)
   arr2
     arr3 = arr2.join(",");
   console.log(arr3.length);
    
   
 }

  frankenSplice([1, 2, 3], [4, 5, 6], 1);

function frankenSplice(arr1, arr2, n) {
  // It's alive. It's alive!
  let arr3 = arr2.slice(0, arr2.length);
  arr3.splice(n, 0, ...arr1);
  
  return arr3;

}

console.log(frankenSplice([1, 2, 3], [4, 5, 6], 1));```

I used slice to create a new non-related copy of arr2, then worked the splice on arr3.