Bind the prototype to the JavaScript object

Question

Bind the prototype to the JavaScript object

Consider this scenario where I have JSON data containing person objects.

[
  {
     "name": "Alice",
     "age": 28,
  },
  {
     "name": "Bob",
     "age": 33
  }
]

Upon parsing, an array with two JavaScript objects is obtained. Suppose I want to add a method called introduce to these objects, which would look something like this:

function introduce() {
  return "My name is " + this.name + " and I am " + this.age + " years old.";
}

One way to achieve this would be iterating over the objects and calling:

person.constructor.prototype.introduce = introduce

However, this approach will make the introduce function accessible to all JavaScript objects, not just the intended ones.

Alternatively, manually attaching the function to each object can be done, but in case of adding more functions later, it would require iterating over all objects again.

Ideally, having a prototype that can be fitted with the introduce method and then connected to all person objects would be preferred. This way, if the prototype is extended in the future, the added functions will also be available to the person objects.

The query now arises: how can this be achieved?

javascript json prototype prototypal-inheritance

Answer 1

Answer №1

My recommendation is to establish a new class:

JSBin

var Individual = (function () {
    function Individual(person) {
        this.person = person;
        this.name = person.name;
        this.age = person.age;
    }
    Individual.prototype.introduction = function () {
        return "I go by the name of " + this.name + " and I am " + this.age + " years old.";
    };
    return Individual;
})();

Answer 2

My recommendation is to establish a new class:

JSBin

var Individual = (function () {
    function Individual(person) {
        this.person = person;
        this.name = person.name;
        this.age = person.age;
    }
    Individual.prototype.introduction = function () {
        return "I go by the name of " + this.name + " and I am " + this.age + " years old.";
    };
    return Individual;
})();

Answer 3

Answer №2

Your query seems a bit unclear, but it appears that you are looking to create a separate "person" class instead of just a regular object:

function Person(obj) {
    this.name = obj.name;
};

Person.prototype.introduce = function() {
    return console.log('Hello, my name is '+this.name);
};

var personA = new Person({ name:'Alice' });
var personB = new Person({ name:'Bob' });

personA.introduce();  // "Hello, my name is Alice"
personB.introduce();  // "Hello, my name is Bob"

Answer 4

Your query seems a bit unclear, but it appears that you are looking to create a separate "person" class instead of just a regular object:

function Person(obj) {
    this.name = obj.name;
};

Person.prototype.introduce = function() {
    return console.log('Hello, my name is '+this.name);
};

var personA = new Person({ name:'Alice' });
var personB = new Person({ name:'Bob' });

personA.introduce();  // "Hello, my name is Alice"
personB.introduce();  // "Hello, my name is Bob"

Answer 5

Answer №3

Create a basic Individual class:

function Individual(name,age){
    this.name = name; 
    this.age = age
}

For example, here is an array of individuals:

var individuals = [
  {
     "name": "Eve",
     "age": 25,
  },
  {
     "name": "Dan",
     "age": 40
  }
];

Transform the individuals array into an array of Individual:

individuals = individuals.map(function(i){
    return new Individual(i.name,i.age)
});

Include the following method to the prototype:

Individual.prototype.greet = greet

Answer 6

Create a basic Individual class:

function Individual(name,age){
    this.name = name; 
    this.age = age
}

For example, here is an array of individuals:

var individuals = [
  {
     "name": "Eve",
     "age": 25,
  },
  {
     "name": "Dan",
     "age": 40
  }
];

Transform the individuals array into an array of Individual:

individuals = individuals.map(function(i){
    return new Individual(i.name,i.age)
});

Include the following method to the prototype:

Individual.prototype.greet = greet

Answer 7

Answer №4

If needed, you have the option to utilize either the outdated deprecated __proto__ property or the more modern ES6 method Object.setPrototypeOf. Keep in mind that it is not recommended to modify an object's prototype directly (as noted here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto), although there are cases where it may be justified.

var you = { name: "Niels B." }
you.__proto__ = { hello: function () { console.log(this.name) } }
you.hello()

In relation to your specific issue:

function Person() {}
Person.prototype = {
  introduce: function () {
    return "My name is " + this.name + " and I am " + this.age + " years old.";
  }
}

Then for each person:

person.__proto__ = Person.prototype;
// or
Object.setPrototypeOf(person, Person.prototype);

For further performance comparisons, refer to this JSPerf: http://jsperf.com/parse-json-into-an-object-and-assign-a-prototype

Additional discussion can be found here: https://groups.google.com/forum/#!topic/ringojs/PxS1O5jMx-8

Answer 8

If needed, you have the option to utilize either the outdated deprecated __proto__ property or the more modern ES6 method Object.setPrototypeOf. Keep in mind that it is not recommended to modify an object's prototype directly (as noted here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto), although there are cases where it may be justified.

var you = { name: "Niels B." }
you.__proto__ = { hello: function () { console.log(this.name) } }
you.hello()

In relation to your specific issue:

function Person() {}
Person.prototype = {
  introduce: function () {
    return "My name is " + this.name + " and I am " + this.age + " years old.";
  }
}

Then for each person:

person.__proto__ = Person.prototype;
// or
Object.setPrototypeOf(person, Person.prototype);

For further performance comparisons, refer to this JSPerf: http://jsperf.com/parse-json-into-an-object-and-assign-a-prototype

Additional discussion can be found here: https://groups.google.com/forum/#!topic/ringojs/PxS1O5jMx-8

Answer 9

Answer №5

Implement a person class using the Person.prototype method:

function Person(name, age){
    this.name = name;
    this.age= age;
}

function introduction() {
  return "Hi, I'm " + this.name + " and I am " + this.age + " years old.";
}

Person.prototype.introduction = introduction;

person1 = new Person ("Alice", 25);
person1.introduction();

Answer 10

Implement a person class using the Person.prototype method:

function Person(name, age){
    this.name = name;
    this.age= age;
}

function introduction() {
  return "Hi, I'm " + this.name + " and I am " + this.age + " years old.";
}

Person.prototype.introduction = introduction;

person1 = new Person ("Alice", 25);
person1.introduction();

Answer 11

Answer №6

One way to organize these individuals is by creating a structured format.

let Person = function Person(info){
 this.name = info.name;
 this.age = info.age;
};
Person.constructor = Person;

Next, you can iterate through to generate the individuals.

let individuals = [];
for(let i = 0; i < data.length; i++){
 individuals.push(new Person(data[i]));
}

Once the individuals have been created, they may need to introduce themselves. You could extend the functionalities of the Person "class".

Person.prototype.introduction = function() {
  return "Greetings! My name is " + this.name + ", and I am " + age + ".";
}

This will enable them to utilize the introduction function:

for(let i = 0; i < individuals.length; i++){
 console.log(individuals[i].introduction());
}

Answer 12

One way to organize these individuals is by creating a structured format.

let Person = function Person(info){
 this.name = info.name;
 this.age = info.age;
};
Person.constructor = Person;

Next, you can iterate through to generate the individuals.

let individuals = [];
for(let i = 0; i < data.length; i++){
 individuals.push(new Person(data[i]));
}

Once the individuals have been created, they may need to introduce themselves. You could extend the functionalities of the Person "class".

Person.prototype.introduction = function() {
  return "Greetings! My name is " + this.name + ", and I am " + age + ".";
}

This will enable them to utilize the introduction function:

for(let i = 0; i < individuals.length; i++){
 console.log(individuals[i].introduction());
}

Answer 13

Answer №7

To avoid reconstructing every time, you can consider the following approach:

let people =[
  {
     "name": "Alice",
     "age": 28,
  },
  {
     "name": "Bob",
     "age": 33
  }
],
i=-1,len=people.length,tmp
,proto={
  sayName: function(){
    console.log("from sayname",this.data.name);
  }
};
while(++i<len){
  tmp=Object.create(proto);
  tmp.data=people[i];
  people[i]=tmp;
}
people[0].sayName();
proto.sayName=function(){console.log("changed it");};
people[1].sayName();

If your JSON objects have a lot of members, this method could potentially save you from duplicating them in your constructor function. However, the performance benefits are uncertain.

Answer 14

To avoid reconstructing every time, you can consider the following approach:

let people =[
  {
     "name": "Alice",
     "age": 28,
  },
  {
     "name": "Bob",
     "age": 33
  }
],
i=-1,len=people.length,tmp
,proto={
  sayName: function(){
    console.log("from sayname",this.data.name);
  }
};
while(++i<len){
  tmp=Object.create(proto);
  tmp.data=people[i];
  people[i]=tmp;
}
people[0].sayName();
proto.sayName=function(){console.log("changed it");};
people[1].sayName();

If your JSON objects have a lot of members, this method could potentially save you from duplicating them in your constructor function. However, the performance benefits are uncertain.

Bind the prototype to the JavaScript object

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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