Basic Algorithm Scripting: Slice and Splice

JavaScript
1

For this challenge, my code is passing all requirements except for: “All elements from the first array should be added to the second array in their original order.” However, when I console.log(concArr2), I seem to be getting the desired array every time. What am I doing wrong?

https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/slice-and-splice

function frankenSplice(arr1, arr2, n) {
  for(let i = 0; i < arr2.length; i++){
    if(i === n){
      let arr3 = arr2.slice(0, n);
      let arr4 = arr2.slice(n, arr2.length);
      let concArr = arr3.concat(arr1);
      let concArr2 = concArr.concat(arr4);
      return concArr2;
    };
  };
};

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

2

Can you format your code and post a link to the challenge?

3

Updated it! Thank you!

4

All elements from the first array should be added to the second array in their original order.

You are not adding them to second array, but to concArr2.

6

Good catch! I guess the code means the same thing but doesn’t accomplish it how FCC wants. Thank you!

1 Like
7

I tried solving it as below

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

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

but FCC keeps on complaining that The second array should remain the same after the function runs. . please clarify what above solution is failing as per FCC ?

8

With this you are not making a copy, just a new reference to the same array, so arr2 is still getting modified.
To create a copy you need to use concat(), slice() or the spread operator

2 Likes
9

Thanks for detailed clarification.

Regards,
Vikram