A function that checks if a string containing brackets is valid.

isValid.js

let isValid = (s) => {
    let bracket_obj = {
        "[":"]",
        "(":")",
        "{":"}"
    };
    let open_brackets = [];
    for (let i = 0; i < s.length; i++) {
        if (s[i] in bracket_obj) {
            open_brackets.push(s[i]);
        } else if(open_brackets.length===0 && bracket_obj[s[i]]=== undefined) {
            return false;
        } else if(bracket_obj[open_brackets[open_brackets.length-1]]===s[i]){
            open_brackets.pop();
        } else { return false; }
    }
    return open_brackets.length === 0;
};

console.log(isValid("([{})]"))
console.log(isValid("({]})"))
console.log(isValid("([{}])"))
console.log(isValid("({[]})"))
console.log(isValid("()[]{}"))
console.log(isValid("}"))