Typescript Basics

We will the basics of TypeScript in this blog post.

This is part of the Typescript Tutorial Series, whose index / TOC is available here → Typescript Tutorial Series.

What is TypeScript

In short, TypeScript is a superset of JavaScript with increased programming features like static type checking, OOP Style programming such Classes, and Interfaces etc.,

It is a new language created by Microsoft and has been widely used in the Frontend Technology like Angular. In fact Angular 2 Framework was entirey rewritten in Typescript, from its predecessor version Angular JS which was written in Javascript.

Typescript Execution Flow

In simple terms, the execution flow of a Typescript program is described in 3 steps as follows. The

  • Source → The Soure code is written in any compatible text editor or IDE with an extension .ts
  • Transpile → The Source code is Transformed and Compiled into a javascript file with an extension .js
  • The Javascript file is executed in a browser or the Node runtime environment

What you need to work with Typescript

You need to have the following to work with Typescript.

Tool Link Description
npm https://npmjs.org/ Node Package Manager to install the typescript via npm install -g tsc to install globally (-g flag) to all the users
tsc http://typescriptlang.org Typescript to transpile the program from the .ts to .js form.
node http://nodejs.org/ Node Runtime to execute the converted the Javascript Program

Command Execution Example

If we have a Helloworld Program in TypeScript, the code execution goes like this.

# Source code written in `helloworld.ts`

# Transpile this program using the `tsc` - TypeScript compiler 
tsc helloworld.ts

# Run the `.js` version of the Program using the Node 
node helloworld.js


Source Codehelloworld.ts

typescriptPractices > type helloworld.ts 
console.log("Hello World!");

Transpile using tsc

typescriptPractices > tsc myhelloworld.ts 

typescriptPractices > ls -l
total 8
-rw-rw-rw-  1 raghs 0 30 2021-06-18 22:20 helloworld.js
-rw-rw-rw-  1 raghs 0 28 2021-06-18 22:18 helloworld.ts

Execute → using node of the .js file generated

typescriptPractices > node helloworld.js
Hello World!

typescriptPractices >


Raghavan alias Saravanan Muthu
19 Jun 2021 | Sat | 16 37 51 PM IST