validation

validation.js

function isValid(inStr = '') {
    var dictionary = {
        '{': '}',
        '(': ')',
        '[': ']'
    }
    var stack = [];
    inStr = inStr.split('');
    for (var i = 0; i < inStr.length; i++) {
        if(!dictionary.hasOwnProperty(inStr[i]) && dictionary[stack[stack.length -1]] == inStr[i]) {
            stack.pop();
        } else if(dictionary.hasOwnProperty(inStr[i])) {
            stack.push(inStr[i]);
        } else {
            return false;
        }
    }
    return true;
}

console.log(isValid('[{}{}{}()]'));             // true
console.log(isValid('[{}{}{]}()]'));            // false
console.log(isValid('[{}{]}{}()]'));            // false
console.log(isValid('[{({})}{[()]}[({})]()]')); // true