JSFiddle - React, Tailwind, and code Playground

JavaScript

//console.log(isIsomorphic("egg", 'add')); // true
//console.log(isIsomorphic("egg", 'sad')); // false
//console.log(isIsomorphic("dgg", 'add')); // true
//console.log(isIsomorphic("paper", 'title'))
//console.log(isIsomorphic("kick", 'side'))
console.log(isIsomorphic('sbc', 'abb'))

function isIsomorphic(firstString, secondString) {
	if (firstString.length !== secondString.length) return false;
	let hash = {};
  
	for (var i = 0; i < firstString.length; i++) {
  	let l_a = firstString[i];
    let l_b = secondString[i];

    if (!hash[l_a]) {
    	if (secondString.indexOf(l_b) < i) {
      	return false
      } else {
      	hash[l_a] = l_b;
      }
    } else if (hash[l_a] !== l_b) {
    	return false;
    }
  }
  
  return true;
  
}