one-char-string-match.js

const strings = [
  'abcde',
  'fghij',
  'klmnop',
  'klnmpo',
  'axcde'
];

const strlen = strings[0].length;

let strIndex1 = 0;
let strIndex2 = 1;

function iter() {
  if (strIndex2 === strings.length) {
    strings.splice(strIndex1, 1);
    strIndex1 = 0;
    strIndex2 = 1;
    iter();
    return;
  }
  
  if (strIndex1 === strings.length) {
    console.log("No strings found"); return;
  }
  
  const str1 = strings[strIndex1];
  const str2 = strings[strIndex2];
  
  let matches = 0;
  for (j = 0; j < strlen; j++) {
    if (str1.charAt(j) !== str2.charAt(j)) {
      matches++;
    }
  }
  
  if (matches === 1) {
    console.log("MATCH! " + str1 + " - " + str2);
    return;
  } else {
    console.log("No match! " + str1 + " - " + str2);
    strIndex2++;
    iter();
    return;
  }
}

iter();