Question: Algorithm Challenge "Missing Letters" Solution

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

I have a question about this solution.
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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