Intermediate Algorithm Scripting - Missing letters

JavaScript
1

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 '“abcdefghijklmnopqrstuvwxyz” should return undefined

2

Formatting applied for human readability:

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 what’s happening? I see an issue when I run this exact code and test case in the console.

Please provide a link to the Challenge when asking a question: https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/missing-letters

3

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 ;

4

Doesn’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?

5

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

6

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?

7

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 }

8

i see, its the unicode after ‘z’ it evaluates true.
thank you

1 Like
9

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?

11

hi, thank you very much

12

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