Object Creation using Constructor Function
A Constructor Function is a special function used to create and initialize objects. It allows values to be passed as parameters during object creation, making it easy to create multiple objects with different data.
What you'll cover
Learning objectives
- Understand Constructor Functions
- Understand Parameterized Constructors
- Create multiple objects
- Understand private properties
- Access object methods
Prerequisites
Related topics
Concept breakdown
What is a Constructor?
A constructor is a function used to create and initialize objects.
Purpose of Constructor
Constructors initialize object properties and assign default or user-supplied values.
Parameterized Constructor
A constructor that receives values through parameters while creating an object.
Object Creation using Constructor Function
> "Customer Id : 1001"> "Customer Name : Sathesh"> "Customer Amount : 1000"> "Customer Id : 1002"> "Customer Name : Ramesh"> "Customer Amount : 2000"
Step by step
- 1
Define Constructor
Create a Customer constructor function with three parameters.
- 2
Initialize Properties
Assign constructor parameters to private variables.
- 3
Create Public Method
Define showData() using the this keyword.
- 4
Create Object
Create the first object using the new keyword.
- 5
Pass Values
Pass customer details while creating the object.
- 6
Display Data
Invoke showData() to display customer information.
- 7
Create Another Object
Reuse the constructor to create another customer object with different values.
Key takeaways
Key points
- Constructor functions act as blueprints for objects.
- Objects are created using the new keyword.
- Constructor parameters initialize object data.
- Private properties are declared using local variables.
- Public methods are created using the this keyword.
- The same constructor can create multiple objects.
Advantages
- Reusable code.
- Easy to create multiple objects.
- Supports encapsulation.
- Initialization during object creation.
- Reduces duplicate code.
Disadvantages
- Each object gets its own copy of methods.
- Consumes more memory than prototype methods.
- ES6 Classes provide a cleaner syntax.
Customer Management System
Every customer record in a banking or shopping application can be represented as an object created using a constructor function.
Frequently asked questions
A Constructor Function is a function used to create and initialize objects.
The new keyword creates a new object and binds this to that object.
A constructor that receives values through parameters during object creation.
Yes. A single constructor function can create any number of objects.
Quick MCQ practice
1. Which keyword creates an object from a constructor function?
2. Constructor parameters are used to?
3. Which keyword is used to create public methods?
Practice on your own
Coding exercise
Employee Constructor
Create an Employee constructor that accepts employeeId, employeeName and salary. Create a showDetails() method and create three employee objects.
Assignment
- Create a Product constructor.
- Accept productId, productName and price.
- Create showProduct() method.
- Create three product objects.
- Display all product details.
Tags
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