# Basic Algorithm Scripting: Mutations **HELP **

Tell us what’s happening:
I am struggling to understand this exercise. I have lowercased the strings in the array and looped through to check if the second string has the index of the first string.

Where did I go wrong?

Your code so far

``````
function mutation(arr) {
let secondArr = arr[1].toLowerCase();
let firstArr = arr[0].toLowerCase();

for(let i = 0; i < arr.length; i++){
if(firstArr.indexOf(secondArr) != -1){
return true;
}
return false;
}
}
mutation(["hello", "hey"]);

``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.122 Safari/537.36`.

Challenge: Mutations

Your `if` inside loop is wrong.
`firstArr` is `hello` and `secondArr` is `hey`, so the conditional is like:

``````'hello'.indexOf('hey') // which is always return false
``````

If you want to loop each letter in firstArr, then you need to loop it like

``````for (let i = 0; i < firstArr.length; i++) {
firstArr[i] // is h
}
``````