Question

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Javascript type of custom object

I have a question regarding JavaScript instances.
Let us consider the following code:

function Box(col)
{
   var color = col;

   this.getColor = function()
   {
       return color;
   };
}

var blueBox=new Box("blue");
console.log(blueBox.getColor())

var greenBox=new Box("green");
console.log(greenBox.getColor())
console.log(typeof(blueBox))
console.log(typeof(greenBox))

Now, when we check the last two statements, the browser prints type as object
How do I check If they are created from same constructor Box?

Answer 1

You can use instanceof like:

var blueBox=new Box("blue");
if (blueBox instanceof Box){
  //yay 4 boxes!
}

In case you want to check two elements you can also compare their constructors:

var blueBox = new Box("blue");
var greenBox = new Box("green");
if (blueBox.constructor === greenBox.constructor){
  //yay 4 same constructors
}