JSFiddle - React, Tailwind, and code Playground

JavaScript

function testBraces(s) {
    for (var i=0, j=0; i<s.length && j>=0; i++)
        switch(s.charAt(i)) {
            case '(': { j++ ; break; }
            case ')': { j-- ; break; }
        }
    
    return j == 0;
}

var strTrue = "(()()())",
    strFalse = "((()())";

alert(testBraces(strTrue));
alert(testBraces(strFalse));