Hello World With TypeScript 2.0

Today, we will be discussing how to set up your first application using TypeScript 2.

Objective

  • What is TypeScript
  • Nodejs installation
  • Install TypeScript
  • Create the first project
  • Run the project

What is TypeScript

TypeScript is a language superset of JavaScript language. It compiles the code as written in the plain JavaScript code. So all the correct JS code is valid in TypeScript. Apart from that, TypeScript provides extra features also which are very useful for writing a good code.

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TypeScript has compiler/transpiler in place which converts code into javascript. Its open source and maintained by Microsoft. It’s continuously evolving and providing better features to developers enforcing them in writing better code.

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Nodejs installation

It’s not a mandatory step for TypeScript. But if you are going to build an Angular application, then it’s a must-do step.

Let’s get started:

  1. Go to https://nodejs.org/en/ this is the official site for node.js.
  2. Click on downloads.

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It will give you options for Windows, Mac, or Linux systems. Download the one in which you would be developing the application.

Once downloaded, double-click on the installer file and follow the steps.

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Let's verify the installation by going to cmd (in Windows) and checking the version

Run the following command.

npm -v

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Now, node.js installation is complete for our requirement.

Install TypeScript

TypeScript can be installed in different ways.

  • If you are not using npm, then directly you can go to https://www.typescriptlang.org/ and download it from there and use it. It is compatible with Visual Studio 2017, Visual Studio 2015. You can use major text editors for the TypeScript editing also.

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Let’s Install TypeScript using npm (node package manager).

Following is the command you need to type in npm command prompt.

npm install -g typescript

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It will install the full package of typescript for the application. It will install always the latest version of the package here. Here, in command, “–g” stands for global, which is saying to install the package at the global level. It will install the TypeScript compiler also. Which plays a very important role in converting the typescript code to native javascript.

Create the first project

Now let’s create the first project in TypeScript2.

Let’s check the version of typescript installed first.

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  1. Run nodejs command prompt as Administrator.
  2. Go to the respective folder in the system where you will be creating the project

    cd <folder path> enter

  3. Run the following code to generate a new project config. in the folder

    tsc -init

    It will create the config file for the project in the respective folder. The name of the file will be tsconfig.json. We will discuss the config file in future articles.

  4. Let’s see the code editors we can use for TypeScript application. There are many good open source code editor for typescript or any js files.

Following are some of the best one which I prefer to use.

You can open your project by going to the folder where it is created.

Run the project

  • Let’s open the folder in Visual Studio code for creating the first project. Get Visual Studio code from here.

    File menu - Open folder

    Select the folder where you have created the config file.
  • Create a new file in the same folder with name,

    HelloWorld.ts
    ts is the extension used for the typescript files. Once the file will be compiled it will create a js file with the same name automatically.
  • In the file write the following code,
    1. var message = "Hello World";  
    2.   
    3. function printIt() {  
    4.     console.log(message);  
    5. }  
    6. printIt();  

  • Let’s build the application.

    Press ctrl+shift+B to build the application
  • This build will create a js file for the respective ts
  • You can open a terminal in visual studio code by clicking ctrl+~
  • You call the following command to run the file

    node HelloWorld
  • You will get “Hello world” printed in the console.

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Conclusion

This is the first article on Exploring TypeScript2. In the next article, we will be looking into the Type annotations, Modules, Interfaces, Namespaces in TypeScript2. Stay tuned!!!

Please let me know your feedback/questions in the comment section.

Happy coding !!!

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