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JavaScript Object-Oriented JavaScript (2015) Introduction to Methods Finishing the Calculator

Mikhailo Rozumovskyy
Mikhailo Rozumovskyy
3,779 Points
Posted by Mikhailo Rozumovskyy
Mikhailo Rozumovskyy
3,779 Points

Why do I recieve [object Object] answer in my CALCULATOR?

I just finished Object Oriented Java Script and trying to put it all together; What should I change? this is my code (it is from one exercise): 

JavaScript
var calculator = {
  sum: 5,
  add: function(value) {
    this.sum += value;
  },
  subtract: function(value) {
    this.sum -= value;
  },
  multiply: function(value) {
    this.sum *= value;
  },
  divide: function(value) {
    this.sum /= value;
  },
  clear: function() {
    this.sum = 0;
  }, 
  equals: function() {
    return this.sum;
  }
}

calculator.add(5);
calculator.equals();
var display = calculator
alert(calculator);

2 Answers

zainsra7
zainsra7
3,237 Points

Hi,

Let's write the code again and see why you're getting that message and what's the solution:

var calculator = {
  sum: 5,
  add: function(value) {
    this.sum += value;
  },
  subtract: function(value) {
    this.sum -= value;
  },
  multiply: function(value) {
    this.sum *= value;
  },
  divide: function(value) {
    this.sum /= value;
  },
  clear: function() {
    this.sum = 0;
  }, 
  equals: function() {
    return this.sum;
  }
}

Above code is simply a calculator object with a bunch of useful methods.

Now let's analyze your code :

calculator.add(5); //This adds 5 to the sum , so after this sum will be 10.
calculator.equals(); //This returns the sum, but you didn't catch it in a variable
var display = calculator 
alert(calculator);  //calculator is an object and with this line you're going to see "[Object object]" in alert dialog box

Let's see the solution:

calculator.add(5); //This adds 5 to the sum , so after this sum will be 10.
var display = calculator.equals(); //equals() method returns sum "10"and we catch it in a variable called display.
alert(display);  //This will now show value of display variable "10" in an alert dialog box.

I hope it answers your question, Happy Coding !

  • Zain
Mikhailo Rozumovskyy
Mikhailo Rozumovskyy
3,779 Points
Mikhailo Rozumovskyy
Mikhailo Rozumovskyy
3,779 Points

ooh, I see, I understand it now. My bad! Thank You!