Польская нотация.js

let input = '(22*3)+1+(3*5)-2';
let result = '';
let stack = [];
let numeral = '0123456789'.split('');
let expression = input + '=';
let operators = '+-*/()'.split('');
let parity = [];
parity['('] = 0;
parity[')'] = 1;
parity['+'] = 2;
parity['-'] = 2;
parity['*'] = 3;
parity['/'] = 3;
for (let i = 0; i < expression.length - 1; i++) {
    if (numeral.indexOf(expression[i]) != -1) {
        result += expression[i];
        if (numeral.indexOf(expression[i + 1]) == -1)
            result += ' ';
    } else {
        if (stack.length == 0) {
            stack.push(expression[i]);
        } else {
            if (expression[i] == '(') {
                stack.push(expression[i]);
            } else {
                if (expression[i] == ')') {
                    while (stack[stack.length - 1] != '(') {
                        result += stack.pop() + ' ';
                    }
                    stack.pop();
                } else {
                    while (parity[stack[stack.length - 1]] >= parity[expression.charAt(i)])
                        result += stack.pop() + ' ';
                    stack.push(expression[i]);
                }
            }
        }
    }
    if (expression[i + 1] == '=') {
        while (stack.length != 0)
            result += stack.pop();
    }
}
console.log(result);
//parity[expression[i]]
//parity[stack[stack.length - 1]]
let rpn = result.split(' ');
for (var i = 0; i < rpn.length; i++) {
    if (!isNaN(Number(rpn[i])) == 1) {
        stack.push(rpn[i]); //засунули в стак все числа
    }
    if (!isNaN(Number(rpn[i])) == 0) {
        if (rpn[i] == '*') {
            stack.push(Number(stack.pop()) * Number(stack.pop()))
        }
        if (rpn[i] == '/') {
            stack.push(Number(stack.pop()) / Number(stack.pop()))
        }
        if (rpn[i] == '+') {
            stack.push(Number(stack.pop()) + Number(stack.pop()))
        }
        if (rpn[i] == '-') {
            stack.push(-Number(stack.pop()) + Number(stack.pop()))
        }

    }
}