calculator.js

/**
 * Declare a function named `calculatorModule`
 * this function will have two private variables declared inside of it.
 * @variable PRIVATE { Number } `memory`
 * @variable PRIVATE { Number } `total`
 * @return {object} `calculator` object that can be used
 */



  /**
   * sets the `total` to the number passed in
   * @param  { Number } x
   * @return { Number }    current total
   */


  /**
   * Return the value of `total`
   * @return { Number }
   */
 function calculatorModule(x){
    //private
    var memory = 0;
    var total = 0;

    var isValid = function(x) {
      if(typeof x === "number") {
        return true;
      } else {
        throw new Error("not a number");
      }
    }
    //public
    return {
      load: function(x) {
        if(isValid(x)){
          total = x;
          return total;
        }
      },
      getTotal: function() {
        return total;
      },
      add: function(x) {
        if(isValid(x)){
          return total += x;
        }
      },
      subtract: function(x) {
        if(isValid(x)){
          return total -= x;
        }
      },
      multiply: function(x) {
        if(isValid(x)){
          return total *= x;
        }
      },
      divide: function(x) {
        if(isValid(x)){
          return total /= x;
        }
      },
      recallMemory: function() {
        return memory;
      },
      saveMemory: function() {
        memory = total;
      },
      clearMemory: function() {
        memory = 0;
      }
    };
 }

 // var myCalculator = calculatorModule();
 // myCalculator.load()
 // console.log(myCalculator.getTotal());

  /**
   * Sums the value passed in with `total`
   * @param { Number } x
   */


  /**
   * Subtracts the value passed in from `total`
   * @param  { Number } x
   */


  /**
   * Multiplies the value by `total`
   * @param  { Number } x
   */


  /**
   * Divides the value passing in by `total`
   * @param  { Number } x
   */


  /**
   * Return the value stored at `memory`
   * @return { Number }
   */


  /**
   * Stores the value of `total` to `memory`
   */


  /**
   * Clear the value stored at `memory`
   */

  /**
   * Validation
   */