Constructor in TypeScript

Constructors are identified with the keyword "constructor". A Constructor is a special type of method of a class and it will be automatically invoked when an instance of the class is created. A class may contain at least one constructor declaration. If a class has no constructor, a constructor is provided automatically. A class can have any number of constructors. When you are using the attribute public or private with constructor parameters, a field is automatically created, which is assigned the value.
Syntax
  1. constructor(ParameterList(Optional)) {
  2. ................
The following example tells you, how to use a constructor in TypeScript. Use the following procedure to create a program using a constructor.
Step 1
Open Visual Studio 2012 and click on "File" menu -> "New" -> "Project". A window will be opened. Specify the name of your application, like "ExampleOfConstructor". Your application will look like:
constructor1-in-TypeScript.jpg
Then click on the OK button.
Step 2
After Step 1 your project has been created. The Solution Explorer, which is at the right side of Visual Studio, contains the js file, ts file, CSS file, and HTML files.
Step 3
The code of the Constructor program:

ExampleOfConstructor.ts

  1. class MyExample {
  2. public Fname: string;
  3. public Lname: string;
  4. constructor(Fname: string, Lname: string) {
  5. this.Fname = Fname;
  6. this.Lname = Lname;
  7. alert("Company name=" + this.Fname + " " + this.Lname);
  8. }
  9. }
  10. window.onload = () => {
  11. var data = new MyExample("Mcn", "Solution");
  12. }
Note In the above-declared program, I have the MyExample class, with a constructor which takes two string value as arguments. When I create an instance of the class (MyExample), the constructor is automatically executed.

default.html

  1. < !DOCTYPEhtml >
  2. <
  3. htmllang = "en"
  4. xmlns = "http://www.w3.org/1999/xhtml" >
  5. <
  6. head >
  7. <
  8. metacharset = "utf-8" / >
  9. <
  10. title > TypeScript HTML App < /title>
  11. <
  12. linkrel = "stylesheet"
  13. href = "app.css"
  14. type = "text/css" / >
  15. <
  16. scriptsrc = "app.js" > < /script>
  17. <
  18. /head>
  19. <
  20. body >
  21. <
  22. h1 > Example of Constructor < /h1>
  23. <
  24. divid = "content" / >
  25. <
  26. /body> <
  27. /html>

app.js

  1. var MyExample = (function() {
  2. function MyExample(Fname, Lname) {
  3. this.Fname = Fname;
  4. this.Lname = Lname;
  5. alert("Company name=" + this.Fname + " " + this.Lname);
  6. }
  7. return MyExample;
  8. })();
  9. window.onload = function() {
  10. var data = new MyExample("Mcn", "Solution");
  11. };
Output:
constructor2-in-TypeScript.jpg