Tonight we have a student asked about what if we return a primitive types in a constructor function, like the below:
function Person() {
this.name = "Roy";
return "abc";
}
What would be the return if we instantiate this constructor?
var me = new Person();
console.log(me); // what would you expect to see??
The result is you will get an instance of "Person". Some people may question "the return was a string, how come it still return an instance of Person?" Well, it is all related to the "new" keyword.
Whenever you instantiate a constructor ( or a Class ) using "new" keyword. The javascript interpreter will enforce you to return an object. If you do not return an object ( just like the above ), the javascript interpreter will enforce this rule by returning an instance of a current constructor.
So it will be similar to the following:
function Person() {
this.name = "Roy";
return this;
//return "abc";
}
However, if you define an object at the return, the javascript interpreter won't care about it.
function Person() {
this.name = "Roy";
return { name: "Joyce" };
}
The above code works because it is returning an object, but it won't be an instance of Person.
So, remember, if you return a "primitive types" in a constructor, when you instantiate the constructor with a "new" keyword, you will always get the instance of the Constructor back. However, if you return an object, you won't have any issue.
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