let x = "farceus";
let y = "character";
const commonCharacters = function (string1, string2) {
let duplicateCharacter = "";
for (let i = 0; i < string1.length; i += 1) {
if (duplicateCharacter.indexOf(string1[i]) === -1) {
if (string2.indexOf(string1[i]) !== -1) {
duplicateCharacter += string1[i];
}
}
}
return [...duplicateCharacter];
};
console.log(commonCharacters(x, y));