Classes, Objects, Properties & Methods - Comparison

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Comparison

Aspect	Class	Object	Property	Method
Definition	A blueprint for creating objects.	An instance of a class.	A variable that holds data within a class or object.	A function defined within a class that operates on the object’s properties.
Role	Defines the structure and behavior of objects.	Represents an entity with its own state and behavior.	Represents the data/state of an object.	Defines actions/behavior for an object.
Nature	Template/blueprint for objects.	Concrete instance with actual data.	Data specific to an object.	Actions that can be performed by an object.
Context	Used to create objects.	Holds data and methods as defined by its class.	Data members of a class or object.	Functions that manipulate object properties.
Creation	Defined using the class keyword.	Created using the new keyword followed by a class constructor.	Declared within a class.	Declared within a class.
Example	class Person { ... }	const person1 = new Person("Alice", 30);	person1.name	person1.greet()

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Detailed Examples

Class

class Person {
    // Properties
    name: string;
    age: number;
 
    // Constructor
    constructor(name: string, age: number) {
        this.name = name;
        this.age = age;
    }
 
    // Method
    greet(): void {
        console.log(`Hello, my name is ${this.name} and I am ${this.age} years old.`);
    }
}

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Object

1. Object Literal

The most straightforward way to create an object is using an object literal.

const person = {
    name: "John Doe",
    age: 25,
    isStudent: true
};

2. Using Interfaces

You can define the shape of an object using an interface and then create an object that adheres to that interface.

interface Person {
    name: string;
    age: number;
    isStudent: boolean;
}
 
const person: Person = {
    name: "John Doe",
    age: 25,
    isStudent: true
};

3. Using Classes

You can define a class and create an instance of that class.

class Person {
    name: string;
    age: number;
    isStudent: boolean;
 
    constructor(name: string, age: number, isStudent: boolean) {
        this.name = name;
        this.age = age;
        this.isStudent = isStudent;
    }
}
 
const person = new Person("John Doe", 25, true);

4. Using Object.create

You can create an object with a specified prototype using Object.create.

const proto = {
    greet() {
        console.log("Hello!");
    }
};
 
const person = Object.create(proto);
person.name = "John Doe";
person.age = 25;
person.isStudent = true;

5. Using Type Aliases

Similar to interfaces, you can use type aliases to define the shape of an object.

type Person = {
    name: string;
    age: number;
    isStudent: boolean;
};
 
const person: Person = {
    name: "John Doe",
    age: 25,
    isStudent: true
};

6. Using Constructors with Interfaces

You can combine constructors and interfaces to create objects.

interface Person {
    name: string;
    age: number;
    isStudent: boolean;
}
 
function createPerson(name: string, age: number, isStudent: boolean): Person {
    return { name, age, isStudent };
}
 
const person = createPerson("John Doe", 25, true);

7. Using Factory Functions

You can use factory functions to create objects.

function createPerson(name: string, age: number, isStudent: boolean) {
    return {
        name,
        age,
        isStudent
    };
}
 
const person = createPerson("John Doe", 25, true);

8. Using Enums

You can use enums to create objects with predefined values.

enum StudentStatus {
    Active,
    Inactive,
    Graduated
}
 
const person = {
    name: "John Doe",
    age: 25,
    status: StudentStatus.Active
};

9. Using Mapped Types

You can use mapped types to create objects dynamically.

type Keys = "name" | "age" | "isStudent";
 
type Person = {
    [K in Keys]: string | number | boolean;
};
 
const person: Person = {
    name: "John Doe",
    age: 25,
    isStudent: true
};

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Property

class Car {
    // Properties
    make: string;
    model: string;
    year: number;
 
    constructor(make: string, model: string, year: number) {
        this.make = make;
        this.model = model;
        this.year = year;
    }
}
 
// Creating an object from the class
const car1 = new Car("Toyota", "Corolla", 2020);
 
// Accessing object properties
console.log(car1.make); // Output: Toyota
console.log(car1.model); // Output: Corolla
console.log(car1.year);  // Output: 2020

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Method

class Car {
    make: string;
    model: string;
    year: number;
 
    constructor(make: string, model: string, year: number) {
        this.make = make;
        this.model = model;
        this.year = year;
    }
 
    // Method defined within the class
    drive(): void {
        console.log(`Driving a ${this.year} ${this.make} ${this.model}`);
    }
}
 
// Creating an object from the class
const car1 = new Car("Toyota", "Corolla", 2020);
 
// Calling a method on the object
car1.drive(); // Output: Driving a 2020 Toyota Corolla

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