Var _extends = (this & this.Again, only one of the attempted instantiations is legitimate. The class Leaf derives the attributes from Root and Child classes by virtue of multi-level inheritance. Var _extends = (this & this._extends) || function (d, b) //indirectly inherits from Root by virtue of inheritance Example: Class InheritanceĬonsole.log("Area of the circle: "+this.Area) However, TypeScript doesn’t support multiple inheritance. SyntaxĬlass child_class_name extends parent_class_name
Child classes inherit all properties and methods except private members and constructors from the parent class. The newly created classes are called the child/sub classes.Ī class inherits from another class using the ‘extends’ keyword. The class that is extended to create newer classes is called the parent class/super class. Inheritance is the ability of a program to create new classes from an existing class. TypeScript supports the concept of Inheritance. Reading attribute value Engine as : XXSY1
The output of the above code is as follows − ’ dot notation (called as the period) to access the data members of a class.Ĭonsole.log("Function displays Engine is : "+this.engine)Ĭonsole.log("Reading attribute value Engine as : "+obj.engine)Ĭonsole.log("Function displays Engine is : " + this.engine) Ĭonsole.log("Reading attribute value Engine as : " + obj.engine) The constructor should be passed values if it is parameterized.Ī class’s attributes and functions can be accessed through the object. The right-hand side of the expression invokes the constructor. The new keyword is responsible for instantiation. The syntax for the same is given below − Syntax To create an instance of the class, use the new keyword followed by the class name. Note that the function keyword is not used here.Ĭonsole.log("Engine is : " + this.engine) Hence to avoid ambiguity, the class’s field is prefixed with the this keyword.ĭisp() is a simple function definition. Here, the parameter name and the name of the class’s field are the same. The this keyword refers to the current instance of the class. A constructor is a function and hence can be parameterized. TypeScript defines a constructor using the constructor keyword. The example above declares a constructor for the class.Ī constructor is a special function of the class that is responsible for initializing the variables of the class. The var keyword is not used while declaring a field. On compiling, it will generate following JavaScript code. These components put together are termed as the data members of the class. They are also at times referred to as methods Fields represent data pertaining to objectsĬonstructors − Responsible for allocating memory for the objects of the classįunctions − Functions represent actions an object can take. The rules for identifiers must be considered while naming a class.Ī class definition can include the following −įields − A field is any variable declared in a class. The class keyword is followed by the class name.
Use the class keyword to declare a class in TypeScript. JavaScript ES5 or earlier didn’t support classes. Typescript gives built in support for this concept called class. A class encapsulates data for the object. A class in terms of OOP is a blueprint for creating objects. TypeScript supports object-oriented programming features like classes, interfaces, etc. TypeScript is object oriented JavaScript.