validParentheses.js

function validParentheses(parens) {
    
    pairLenght = parens.length;

    for (let i = 0; i < pairLenght; i++) {
        parens = parens.replace('()','');   
    }

    return parens.length < 1;
}

console.log(validParentheses('(()'));
console.log(validParentheses('(())((()())())'));