# Question: Algorithm Challenge "Missing Letters" Solution

Continuing the discussion from freeCodeCamp Algorithm Challenge Guide: Missing Letters:

I cannot understand below line.
Variation “Compare” has two values? why there is comma(,) ?

``````var compare = str.charCodeAt(0), missing;
``````

It’s a shorthand for this:

``````var compare = str.charCodeAt(0);
var missing;
``````
1 Like
``````function fearNotLetter(str) {
let alpha = "abcdefghijklmnopqrstuvwxyz".split('');
let missing = '';
let i = alpha.indexOf(str[0]);
let j = 0;
for(; i < alpha.length; i++){
if(alpha[i] !== str[j]){
missing = alpha[i];
return missing;
}
j++;
}
return;
}

fearNotLetter("abce");
``````

my solution, not really optimal but easy to understand.

Here is my solution for the “Missing Letters” problem:

``````function fearNotLetter(str) {
const letters = "abcdefghijklmnopqrstuvwxyz";
const searchStr = letters.substring(letters.indexOf(str[0]), letters.indexOf(str[str.length - 1]));
const result = searchStr.split('').filter(l => !str.includes(l));
return result.length ? result.join() : undefined;
}
fearNotLetter("abce");
``````
``````function fearNotLetter(str) {
let alpha = 'abcdefghijklmnopqrstuvwxyz'
let splitedAlpha = alpha.split("");
let splitedString = str.split("");
let strLen = str.length;
let indexInAlpha = alpha.indexOf(str[0]);
let returnedString = splitedAlpha.splice(indexInAlpha,strLen);

for (let j=0; j<strLen; j++){
if(splitedString[j]===returnedString[j]){
continue;
}
else{
console.log(returnedString[j]);
return returnedString[j];
}

}
return undefined;
}

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

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