Day 9 : TypeScript

 

Constructor :

• Constructor is a special type of  method or function which is called at the time of object creation.
• The constructor method is always defined with "constructor" keyword.
• The class always having a constructor is not needed or necessary.
• The members of the class in a constructor are accessed using "this" keyword.
• Syntax :

constructor () {

//statements

                                                              }

• Example :

    

Access Modifiers :

• The access modifiers are used for controlling the visibility or availability of its data members.
• Mainly their are three types of access modifiers :

1) Public :

• By default, all members or functions of class are public.
• Public members are accessible anywhere in the program.

2) Private :

• The private members are accessible only within the class and its child class.
• If we create a object of private member outside the class, it will give compile error.

3) Protected :

• The protected members are accessible within class and inherited class.

Example of access modifiers :

Inheritance :

• Creating a new class(derived class) from existing class(base class) is called as inheritance.
• The class whose members are inherited is called as parent/base class.
• The class who inherits those members is called as child/derived class.
• The "extends" keyword is used in TS for inheritance.
• We use inheritance for method overriding and code reusability.
• Their are 5 types of inheritance :

1. Single Inheritance
2. Multilevel Inheritance
3. Multiple Inheritance
4. Hybrid Inheritance
5. Hierarchical Inheritance

• But TS supports only single and multilevel inheritance.

1) Single Inheritance :

• Deriving a new class from base class is called as single inheritance.
• The single inheritance inherits the properties of at most one parent class.
• In single inheritance, the derived class inherits methods of base class as well as add new methods in existing program.

2) Multilevel Inheritance :  

• Deriving a new class from derived one is called as multilevel inheritance.
• The multilevel inheritance inherits properties of more than one parent class.
• In multilevel inheritance, the derived class inherits properties of both derived and base class.

Example :

Thank You!!!

For more understanding watch below video :

Angular

JavaScript Day 1 : Day 1

JavaScript Day 2 Global Pollution : Day 2 Global

JavaScript Day 2  Undefined and Hoisting : Day 2 Undefined

JavaScript Day 3 : Day 3

JavaScript Day 4 : Day 4

JavaScript Day 5 : Day 5

JavaScript Day 6 : Day 6

TypeScript Day 7 : Day 7

TypeScript Day 8 : Day 8