CODEWITHSUNDEEP
javascript
zero298
zero298

Reputation: 26867

How can I get the name of the type of this object in JavaScript?

How can I get the type name of an instantiated object whenever it has been through a namespace?

Consider these two ways of declaring inheritence:

Outside of a module

With this way, there is a function object that is named Shark so whenever I ask for myShark.constructor.name, it returns the name of the function that constructor is referencing, which is Shark.

// Fish
function Fish() {
   this.fins;
}
Fish.prototype.swim = function() {
   console.log("Swim");
};

// Shark
function Shark() {
   this.teeth;
}
Shark.prototype = new Fish;
Shark.prototype.constructor = Shark;

var myShark = new Shark();
console.log("My shark is: " + myShark.constructor.name);
// Prints => My shark is: Shark

Inside a module

That's all fine, but whenever I declare an inheritance structure inside of a module, I usually structure it as below. The problem with this is that the constructor for Yacht references an anonymous function. Therefore, whenever I ask for the myBoat.constructor.name it has an empty string. Is there a way that I can still get a String representation of the object's type?

var boats = (function() {
   exports = {};

   // Boat
   exports.Boat = function() {
      this.crew = 1;
   };
   exports.Boat.prototype.sail = function() {
      console.log("Sail");
   };

   // Yacht
   exports.Yacht = function() {
      this.decks = 4;
   };
   exports.Yacht.prototype = new exports.Boat;
   exports.Yacht.prototype.constructor = exports.Yacht;

   return exports;
}());

var myYacht = new boats.Yacht();
console.log("My boat is: " + myYacht.constructor.name);
// Prints => My boat is:

I have considered changing how I declare inheritance so that I create named functions inside the module and then expose them through exports as below. Is there any other way to get the same result without having to make named functions and then attaching them to exports?

var drinks = (function() {
   var exports = {};

   // Drink
   function Drink() {
      this.calories = 130;
   }

   // Beer
   function Beer() {
      this.alcohol = 8;
   }
   Beer.prototype = new Drink;
   Beer.prototype.constructor = Beer;

   exports.Drink = Drink;
   exports.Beer = Beer;

   return exports;
}());

var myBeer = new drinks.Beer();
console.log("My drink is: " + myBeer.constructor.name);
// Prints => My drink is: Beer

Upvotes: 1

Views: 74

Answers (1)

raina77ow
raina77ow

Reputation: 106365

An alternative would be using names in function expressions:

// Yacht
exports.Yacht = function Yacht() {
   this.decks = 4;
};
exports.Yacht.prototype = new exports.Boat;
exports.Yacht.prototype.constructor = exports.Yacht; 
// incorrect: exports.Yacht.prototype.constructor = Yacht
// as the name is not in the scope

// ...
var myYacht = new boats.Yacht();
console.log("My boat is: " + myYacht.constructor.name);
// My boat is: Yacht

Note that adding the name to that function won't introduce Yacht into the main function's scope, so it's not the same as function declaration approach used in your third code snippet. Besides, it's more concise. )

Upvotes: 1

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