CODEWITHSUNDEEP
javascript
Carlos Costa
Carlos Costa

Reputation: 21

Equivalence of object constructors

Often, when I create an object in Javascscript, I will do something like this:

function getObj(property) {
    return {
        property,
        displayProp: function() {
            console.log(this.property);
        }
    }
}

let obj = getObj("Hello World!);

I know that the usual way to create a constructor would be as such:

function getObj(property) {
    this.property = property;
    this.displayProp = function() {
        console.log(this.property);
    }
}

let obj = new getObj("Hello World!);

Now, my question is, are these two methods equivalent. As far as I can tell, they are the same, and you can also use the 'new' keyword when creating an object using the first case. For me, the first case makes more sense, but it doesn't matter too much to me. Thanks.

Upvotes: 1

Views: 42

Answers (1)

Peterrabbit
Peterrabbit

Reputation: 2247

The first example is a function that returns a litteral object (which constructor will remain simply "Object").

The second one creates a new constructor.

function getObj(property) {
    return {
        property,
        displayProp: function() {
            console.log(this.property);
        }
    }
}

// this will be useless because the prototype of getObj is not related to the returned object
getObj.prototype.test_prop = "Test prop"; 

let obj = getObj("Hello World!");
console.log(obj.constructor.name) // Object
console.log(obj.test_prop) // undefined

function Obj(property) {
    this.property = property;
    this.displayProp = function() {
        console.log(this.property);
    }
}

Obj.prototype.test_prop = "Test prop";

obj = new Obj("Hello World!");
console.log(obj.constructor.name) // Obj
console.log(obj.test_prop) // Test prop

Upvotes: 1

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