Is the input word in alphabetical order?

I'm writing a function that will return true or false in regards to whether or not the input string is in alphabetical order. I'm getting undefined and not sure what I'm missing

function is_alphabetic(str) {
  let result = true;
  for (let count = 1, other_count = 2; count >= str.length - 1, other_count >= str.length; count++,
    other_count++) {
    if (str.at[count] > str.at[other_count]) {
      let result = false
    }
    return result
  }
}
console.log(is_alphabetic('abc'));

you have put return statement inside the for loop, it should be outside the loop body.

Your code is also not correct. count should start from 0, other_count should start from 1.

count >= str.length - 1 should be count < str.length - 1 (this condition is completely unnecessary in your code because other_count < str.length should be the terminating condition in the loop)

and

other_count >= str.length should be other_count < str.length

Here's your corrected code

function is_alphabetic(str) {
  let result = true;

  for (let count = 0, other_count = 1; other_count < str.length; count++, other_count++) {
      if (str[count] > str[other_count]) {
         result = false
      }
  }

  return result;
}

console.log(is_alphabetic('abc'));

Here's an alternative approach

function is_alphabetic(str){
   return str.split('')
             .every((c, idx) => str[idx + 1] ? c < str[idx + 1] : true);
}

console.log(is_alphabetic('abc'));

Keep in mind that if you want the comparisons between the characters to be case-insensitive, then convert the string in to lowercase before comparing the characters.