Valid Parentheses

LeetCode題目: 20. Valid Parentheses

My solution:

/**
 * @param {string} s
 * @return {boolean}
 */
let isValid = s => {
    const dict = {
        '(':')',
        '[':']',
        '{':'}'
    };
    let stack = [];
    for (let i=0; i<s.length; i++) {
        if(dict[s[i]]) stack.push(dict[s[i]]);
        else if(stack.at(-1) === s[i]) stack.pop();
        else return false;
    }
    return stack.length === 0;
};