Valide Parentheses

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
    if(s.length%2!==0){return false};
    let leftActers = ["(","{","["],
        rightActers = [")","}","]"],
        index = 0,
        key = 0,
        stack = [];
        let position = null;
    this.check = (elem)=>{
        if(leftActers.includes(elem)){
            console.log(elem);
            position = leftActers.indexOf(elem);
            stack.push(position);
            index++;
            key++;
            return check(s[key]);
        }
        if(elem===rightActers[stack[stack.length-1]]){
            console.log(elem);
            stack.pop();
            index--;
            key++;
            if(stack.length===0&&index===0&&s[key]===undefined){return true}
            else{return check(s[key])}
        }
        else{
            return false;
        }    
    }
    return check(s[key]);
};

console.log(isValid("{()()}()"));