Valid Parentheses Solution

validParentheses.ts

function isValid(s: string): boolean {
    const stack: string[] = []
    const pairs: Record<string,string> = {
        ')' : '(',
        '}' : '{',
        ']' : '['
    }
    
    for (let i = 0; i < s.length;i++) {
        if (pairs[s[i]] === undefined) {
            stack.push(s[i])
        } else {
            if (stack.length > 0 && stack[stack.length - 1] === pairs[s[i]]) {
                stack.pop()
            } else return false
        }
    }
    return stack.length === 0
};