what is the difference between a method within JS function and to it's prototype?

Question

As output of both the below JS class is same, then what is special here with prototype?

One of the feature of prototype is get rid of duplicate code, in what case this is possible with prototype?

1.

   function Person(name) {
        this.name = name;
        this.sayName = function () {
            console.log(this.name);
        };
    }
    var person1 = new Person("Nicholas");
    person1.sayName();

2.

 function Person(name) {
        this.name = name;
    }
    Person.prototype.sayName = function () {
        console.log(this.name);
    };
    var person1 = new Person("Nicholas");
    person1.sayName();

Number 1 is a method that belongs to the class. Number 2 is a method that belongs to an instantiated object. — Jonathan Eustace, Apr 24 '16 at 15:04

Rajaprabhu Aravindasamy · Accepted Answer · 2016-04-24T15:37:25.407

0

If you assign a property by using prototype then those properties will be shared through out all the instances of the class/constructor which has the particular prototype. But assigning a property using this inside of the constructor will be instance-specific. They cannot be shared with other instances. Each instances will have their own value in it.

edited Apr 24 '16 at 15:37

answered Apr 24 '16 at 15:05

Rajaprabhu Aravindasamy

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Nothing is "private" when it's a property? – Bergi Apr 24 '16 at 15:13
1

@Bergi What I meant was, those properties are private to the instance. Other instances cannot share it. Every instances have their own value in those properties. – Rajaprabhu Aravindasamy Apr 24 '16 at 15:21
1

They don't share it with other instances, yes, but "private" usually means that those "cannot access it". I'd recommend to use the term "instance-specific" instead. – Bergi Apr 24 '16 at 15:31
@Bergi Thanks for suggesting the right term to describe it. – Rajaprabhu Aravindasamy Apr 24 '16 at 15:38

what is the difference between a method within JS function and to it's prototype?

1 Answers1