如何调用与类中方法同名的构造函数原型的基方法？

Question

Given that I have:

var PersonClass = function () {
    function Person(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;

        this.name = function(){
            return this.firstName + " " + this.lastName;
        };

        this.setName = function(a,b){
            this.firstName = a;
            this.lastName = b;
            return this.firstName + " " + this.lastName;
        }
    }

    Person.prototype.name = function () {
        return "Proto_:"+this.firstName + " " + this.lastName;
    };

    Person.prototype.whoAreYou = function () {
        return "Hi i'm " + this.name();
    };

    Person.prototype.setName2 = function(a,b){
        this.firstName = a;
        this.lastName = b;
    };

    return Person;
}(); //PersonClass

And I create an instance: Me = new PersonClass("Steve","Benj"); me.name() // returns Steve Benj. What will call the prototype name method and return Proto_:Steve Benj ?

Answer 1

The function defined in the Person constructor will overwrite/override the prototype definition that occurs below it, so there is no good way to invoke the prototyped function over the function defined in the constructor (see comments on your post for the "bad" way).

I would think about whether or not you want to use the same name for both of these functions, unless this is not your actual use case. I would say you would want to create a prototype function that is called protoName or something like that, if you want different behavior you should define different functions.

Answer 2

The way you structure this, you invoked PersonClass function immediately after it's defined.

So PersonClass === Person .

So when you do Me = new PersonClass("Steve","Benj"); , what you are really doing is Me = new Person('Steve', 'Benj');

So whenever you invoke those prototype methods, you are calling the prototype methods from Person .

You can verify this by doing

Me.constructor // => Person

Answer 3

The relation between object and its prototype lies through constructor property.
In your case the counstructor is Person function object.
Person has direct coupling with its prototype .
The last thing is to call a prototype method over a certain object to bind this keyword properly - and this can be achieved with Function.prototype.call() approach:

console.log(Me.constructor.prototype.name.call(Me));

The output will be:

Proto_:Steve Benj

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The alternative approach is using Object.getPrototypeOf(x) function which would give the same result:

Object.getPrototypeOf(Me).name.call(Me)