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. In the next article of this tutorial series, we will discuss interface.TypeScript is object oriented JavaScript.
TYPESCRIPT CLASS CONSTRUCTOR HOW TO
Then we discussed how to call a base class constructor by passing the respective values to it. We learned how to inherit a class from a base class in TypeScript using the extends keyword. let employee: Employee = new Employee("Kunal",Ĭonsole.log(employee.toString()) Summary So, when you call the toString() method of the derived class, it will print out both the properties. In the implementation of the Employee class constructor, we called the base class constructor to pass the first name and last name of the employee.
TYPESCRIPT CLASS CONSTRUCTOR CODE
Now, in the following code snippet, we created the instance of the Employee class and passed four parameters to its constructor. For example, super(fName, lName) in Employee class constructor calls the base class constructor by passing the parameter values fName and lName. In the derived class super(.) can be used to call the constructor of the base class. Here the Employee class inherits its base Person by writing class Employee extends Person.
Consider the following example to understand it better.
Just use the extends keyword to perform inheritance. In TypeScript, you can inherit a class from another class. In this article of the TypeScript Tutorial for beginners series, we will learn how to inherit a TypeScript class. We have also learned how to create a constructor and how to instantiate a class object. In the last article, we learned how to create a class in TypeScript. Just like any other OOP supported language, TypeScript also allows you to inherit a base class.
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