# Why doesn't my first solution work? Slice and Splice

Tell us what’s happening:
My first attempt at this challenge failed. With a small tweak to the code, I have a solution that passes. I’ve seen that often you can write something like `return someVar.toUpperCase();` and it will return the variable in all caps. You don’t have to convert to upper case before returning the solution. In this challenge, it fails when I don’t splice before returning the solution and I don’t understand why. I may be overlooking the obvious, so I could use some help. Thanks!

``````// this passes the challenge
function frankenSplice(arr1, arr2, n) {
let newArr = [...arr2];
newArr.splice(n, 0, ...arr1);
return newArr;
}

// this fails the challenge
function frankenSplice(arr1, arr2, n) {
let newArr = [...arr2];
return newArr.splice(n, 0, ...arr1);
}
``````
``````  **Your browser information:**
``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0`.

Challenge: Slice and Splice

HI @latechlogan !

Welcome to the forum!

If you console.log the two answers you will see why your first attempt didn’t work.

Correct

``````function frankenSplice(arr1, arr2, n) {
let newArr = [...arr2];
newArr.splice(n, 0, ...arr1);
console.log(newArr) // [ 4, 1, 2, 3, 5, 6 ]
return newArr;
}

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

Incorrect

``````function frankenSplice(arr1, arr2, n) {
let newArr = [...arr2];
console.log(newArr.splice(n, 0, ...arr1)) //[]
return newArr.splice(n, 0, ...arr1);
}

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

If you see unexpected behaviour, check what the method returns. `.toUpperCase()`, returns the new uppercase string, `.slice()` returns the part that you sliced out of the original array, but `.splice()` returns the deleted items from the array, not the new array:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice

Ah, I see… I forgot that the return value can be different from the result of the method. Thanks for your help!

Thanks for your help! I did actually console.log my first solution and was seeing that the result was an empty array. I just couldn’t figure out why that was the result. In fact, I was changing the delete count to see if I could figure out what was going on and saw that deleting items actually filled the array. I didn’t quite connect the dots that I was getting the return value of splice instead of the result of the splice as jsdisco pointed out.

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