Difference between javascript object and function

Question

object 1:

var vehicle = {
        name : "car",
        wheels : 4,
        fuel : "petrol"  
}

object 2:

var vehicle = function(){
    this.name = "car",
    this.wheels = 4,
    this.fuel = "petrol"   
}

When both of the objects describe the object vehicle in the same way, what is the difference between them?

Answer 1

When both of the objects describe the object vehicle in the same way, what is the difference between them?

They don't. Your first vehicle is an object; vehicle.wheels is 4 . Your second vehicle is a function (also an object, but that's not really relevant here); vehicle.wheels is undefined because that function doesn't have a wheels property. You'd have to use var v = new vehicle(); and then v.wheels .

Use object initializers (your first example) when you need a one-off object. Use a function (like your second example) if you need a factory for objects that have the same shape.

Note that if your factory is a constructor function (a function that expects to be called with new , such as your vehicle function), it should be initially capitalized by (overwhelming) convention.

But your factory doesn't have to be a constructor function, it could be a function that just returns an object, in which case you woulnd't use it with new , wouldn't use this inside it, and wouldn't typically capitalize it. Eg:

var vehicle = function(){
    return {
        name: "car",
        wheels: 4,
        fuel: "petrol"   
    };
}

(It could use Object.create if it wanted to assign the object a specific prototype.) Whether you use that and var v = vehicle(); or a constructor function and var v = new Vehicle(); is mostly a matter of style.

Answer 2

The object in JavaScript refers to any entity or a data element. Whereas, a function is a procedure to be performed to achieve something. A function may or may not return an object.

In this case, it looks confusing as they both are used for the same purpose. But, generally this is not how a function is used.

Answer 3

You can create a new instance of this function/class.

var vehicle = function(){
    this.name = "car",
    this.wheels = 4,
    this.fuel = "petrol"   
}

Function/Class Objects can be instanciated.

var v1 = new vehicle(); //Here v1 is an instance of vehicle
console.log(v1.name); // Car

In this case you can not create a new instance of this Object. It's just an Object.

var vehicle = {
        name : "car",
        wheels : 4,
        fuel : "petrol"  
}

Answer 4

Amrinder is right. With the first example you create an object

var vehicle = 
{
    name : "car",
    wheels : 4,
    fuel : "petrol"  
}
//vehicle.name shows "car"

If you use option 2 you create a function which you can call to create an object with the given values:

var vehicle2 = function()
{
        this.name = "car",
        this.wheels = 4,
        this.fuel = "petrol"   
}
var vehicle = new vehicle2(); 
//vehicle.name shows "car"

Answer 5

1. Object --> has property
2. function --> return some value/object do some manuplication with Objects

 var vehicle = { name : "car", wheels : 4, fuel : "petrol" } typeOf(vehicle) // returns "Object" var vehicle = function(){ this.name = "car", this.wheels = 4, this.fuel = "petrol" } typeof(vehicle) // output "function"