Calculator

calc

function Calculator() {
}

Calculator.prototype.calc = function(str) {
    var signs = ["*", "+","/"];         // signs in the order in which they should be evaluated
    var funcs = [multiply, add, divide];                 // the functions associated with the signs
    var tokens = str.split(" ");      // split the string into "tokens" (numbers or signs)
    console.log(tokens)
    for (var round = 0; round < signs.length; round++) {          // do this for every sign
        for (var place = 0; place < tokens.length; place++) {    // do this for every token
            if (tokens[place] == signs[round]) {                         // a sign is found
                var a = parseFloat(tokens[place - 1]);    // convert previous token to number
                var b = parseFloat(tokens[place + 1]);        // convert next token to number
                var result = funcs[round](a, b);           // call the appropriate function
                tokens[place - 1] = result.toString();      // store the result as a string
                tokens.splice(place--, 2);  // delete obsolete tokens and back up one place
            }
        }
    }
    return tokens[0];                  // at the end tokens[] has only one item: the result

    function multiply(x, y) {                   // the functions which actually do the math
        return x * y;
    }

    function add(x, y) {                        // the functions which actually do the math
        return x + y;
    }
    function divide(x, y) {                        // the functions which actually do the math
        return x / y;
    }
}

Calculator.prototype.calcWithVars = function(inputList) {
  // IMPLEMENT ME
}


function main() {
  var calculator = new Calculator();

  console.log("First Step");
  console.log(calculator.calc("3 + 4 * 5 / 7"));

  console.log("Second Step");
  console.log(calculator.calc("( 3 + 4 ) * 5 / 7"));

  console.log("Third Step");
  console.log(calculator.calcWithVars(
        ["pi = 3",
         "pizza = 9 * 9 * pi"]));
}

main();

// Please do not modify the following line.
var module = module || {};
module.exports = Calculator;