# Intermediate Algorithm Scripting - Missing letters

Hi there , cant understand why i am not returning undefined for the last test

heres the challange :

heres my code

``````function fearNotLetter(str) {

let arr= str.split('');
let allpresent=true;
console.log(allpresent);

for(let i=0 ;i<arr.length;i++){
if(str.charCodeAt(i)+1!==(str.charCodeAt(i+1))){
let char = String.fromCharCode(str.charCodeAt(i)+1);
console.log(char);
allpresent=false;
return char;
}
else{console.log(allpresent+i);}
}
if(allpresent){
return ;
}

}

fearNotLetter("abcdefghijklmnopqrstuvwxyz");
``````

passing all tests except 'âabcdefghijklmnopqrstuvwxyzâ should return undefined

``````function fearNotLetter(str) {
let arr = str.split('');
let allpresent = true;
console.log(allpresent);

for (let i = 0; i < arr.length; i++) {
if (str.charCodeAt(i)+1 !== (str.charCodeAt(i+1))) {
let char = String.fromCharCode(str.charCodeAt(i)+1);
console.log(char);
allpresent = false;
return char;
} else {
console.log(allpresent + i);
}
}
if (allpresent) {
return;
}
}

fearNotLetter("abcdefghijklmnopqrstuvwxyz");
``````

Can you explain what you have done so far to troubleshoot whatâs happening? I see an issue when I run this exact code and test case in the console.

i have double checked that my if statement is correct , i have tried to log char , and allpresent to make sure that 1: char is not logging ergo the condition is evaluating false
2 allpresent is evaluating to true ergo we should return undefined ;

Doesnât you console show this output?

``````true
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
{
``````

What looks odd here?

i replaced ( allpresent+i) with (allpresent, i)

``````true
true 0
true 1
true 2
true 3
true 4
true 5
true 6
true 7
true 8
true 9
true 10
true 11
true 12
true 13
true 14
true 15
true 16
true 17
true 18
true 19
true 20
true 21
true 22
true 23
true 24
{
``````

n i am getting this which seems more like the output i expect owvere that curly brace is what i imagine the problem is

Ok, so that seems to be coming after you see `true 24`. That means `i` is 25 when you are getting the `}`? This is a problem. Why is this a problem? is `i + 1 === 26` a valid index for `str`?

does { mean anything ??

i thought there might be a problem when i 25 is compared because there is no i 26. but i imagined it would evaluate to false and go to the else statement, which it does but prints the }

i see, its the unicode after âzâ it evaluates true.
thank you

1 Like

hi just for clarity could i ask what something is compared to if it is compared to an item outside of the bounds of the array?

hi, thank you very much

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