JSFiddle - React, Tailwind, and code Playground

JavaScript

function duplicateEncode(word){
    return [...word.toLowerCase()]
    .map((l, i, arr) => arr.filter(c => c === l).length === 1 
      ? '(' : ')').join``;
}

console.log('(((' === duplicateEncode('din'));
console.log('()()()' === duplicateEncode("recede"));
console.log(")())())" === duplicateEncode("Success"));
console.log("))((" === duplicateEncode("(( @"));