const str = '({[]})[';

const pairs = {
    ')' : '(',
    '}' : '{',
    ']' : '['
}

function isValid(str){
    const stack =[];
    for (let s of str) {
        if(s == '(' || s == '{' || s == '['){
            stack.push(s);
        } else{
            console.log(s, pairs[s])
            if(pairs[s] !== stack.pop() ){
                return false;
            }
        }
    }
    return stack.length == 0
}

const result = isValid(str);
console.log(result)