Use of ‘prototype’ Vs. ‘this’ in Javascript?

When working with JavaScript, you may come across the terms ‘prototype’ and ‘this’. These two concepts play a crucial role in JavaScript programming, but they serve different purposes. In this blog post, we will explore the use of ‘prototype’ and ‘this’ in JavaScript and understand when to use each.

Understanding ‘prototype’

In JavaScript, every object is linked to a prototype object. The prototype object acts as a blueprint for the object and defines its properties and methods. When a property or method is accessed on an object, JavaScript first checks if it exists on the object itself. If not, it looks for it in the prototype object.

The ‘prototype’ property is used to add properties and methods to an object’s prototype. It allows you to define shared properties and methods that can be accessed by all instances of the object.

Here’s an example:

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

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

var person1 = new Person('John');
var person2 = new Person('Jane');

person1.greet(); // Output: Hello, my name is John
person2.greet(); // Output: Hello, my name is Jane

In the above example, the ‘Person’ function acts as a constructor for creating person objects. The ‘greet’ method is added to the ‘Person.prototype’, making it accessible to all person objects. This way, we can avoid duplicating the ‘greet’ method for each person object.

Understanding ‘this’

The ‘this’ keyword refers to the current object being executed or the object that the function is a method of. It allows you to access the properties and methods of the current object within the function.

Here’s an example:

var person = {
  name: 'John',
  greet: function() {
    console.log('Hello, my name is ' + this.name);
  }
};

person.greet(); // Output: Hello, my name is John

In the above example, the ‘greet’ function is a method of the ‘person’ object. The ‘this’ keyword refers to the ‘person’ object, allowing us to access the ‘name’ property using ‘this.name’.

When to use ‘prototype’ vs. ‘this’

The choice between using ‘prototype’ or ‘this’ depends on the specific use case and the desired behavior.

Use ‘prototype’ when:

• You want to define shared properties and methods for all instances of an object.
• You want to save memory by avoiding duplicating properties and methods for each instance.

Use ‘this’ when:

• You want to access properties and methods of the current object within a method.
• You want to dynamically refer to different objects based on the context.

It’s important to note that ‘prototype’ is used in constructor functions to define shared properties and methods, while ‘this’ is used within object literals or methods to refer to the current object.

By understanding the use of ‘prototype’ and ‘this’ in JavaScript, you can write more efficient and maintainable code. Remember to choose the appropriate approach based on your specific requirements.