reverse polish notation

reversepolish.js

// a script that processes arithmetic in reverse polish notation
//https://en.wikipedia.org/wiki/Reverse_Polish_notation

const operate = {
    '+': (a,b) => a+b,
    '-': (a,b) => a-b,
    '*': (a,b) => a*b,
    '/': (a,b) => a/b,
};

const OPERATORS = Object.keys(operate);

function reversePolish(str) {
    let nums = [];

    let parts = str.split(' ');

    for(let part of parts) {
        if(OPERATORS.includes(part)) {
            let operandA = nums.pop();
            let operandB = nums.pop();

            nums.push(operate[part].call(null, operandB, operandA));
        }else {
            nums.push(parseInt(part, 10)); //number
        }
    }

    return parseInt(nums[0], 10);
}

console.log(reversePolish("5 3 * 2 +")); //17