1. Install Node.js:
   TypeScript requires Node.js. If you don't have it installed, download and install Node.js from the official website: https://nodejs.org/
2. Install TypeScript using npm:
   Once Node.js is installed, open your terminal or command prompt and run the following command to install TypeScript globally on your system:
   npm install -g typescript
   The -g flag ensures that TypeScript is installed globally, making it accessible from any directory in your system.
3. Verify TypeScript Installation:
   After the installation is complete, you can check the TypeScript version to ensure it was installed successfully. Run the following command:
   tsc --version
   This will display the version number of TypeScript installed on your system.
4. Create a TypeScript File:
   Now that TypeScript is installed, let's create a simple TypeScript file. Create a new file with a .ts extension, for example, app.ts.
5. Write TypeScript Code:
   Open the app.ts file in a code editor and add the following TypeScript code:
   

   function greet(name: string) { console.log(`Hello, ${name}!`); } 
   let personName: string = "Arham"; greet(personName);

   In this example, we have a function greet that takes a name parameter of type string and logs a greeting to the console.
6. Compile TypeScript to JavaScript:
   TypeScript code needs to be compiled to JavaScript before it can be executed in the browser or Node.js. Run the following command to compile the app.ts file:
   tsc app.ts
   This will create a new file called app.js, which contains the JavaScript code generated from your TypeScript code.
7. Run the JavaScript Code:
   You can now run the generated JavaScript code using Node.js:
   node app.js
   The output should be:
   

   Hello, Arham!

Congratulations! You've successfully installed TypeScript and run your first TypeScript program.

It is a statically typed language.

We have to explicitly tell the type of data, for example:

let firstValue:number=5; 

We can also give a type to one variable to another, for example:

let someVar=10; let newVar:someVar=123; 

This will check the type of data stored in someVar and then assign that to newVar.

The following example will take any type and convert it into the specified type:

let something:any=100; let anotherOne=something as number; OR let anotherOne=<number>something; 

We can declare arrays with a specific type:

let arr:string[]=["hello","world","string_type"]; OR let arr:Array<string>=["hello","world","string_type"]; 

Tuples hold multiple data just like arrays, but they can have different types of data:

let tup:[string,string,number]=["typescript","learning",10]; 

We can also make an array of tuples:

let arrOfTup:[number,string][]=[[5,"bannaa"],[10,"apples"]]; 

We can declare the inputs and specify the type of outputs needed as a return from the function:

function sum(firstNum:number,secNum:number):number{ return firstNum+secNum; } 

If we don't want to return anything from a function, we can use void:

function noReturn(firstNum:number,secNum:number):void{ //this shouldn't return anything } 

This allows us to declare constants with numeric or string values:

enum bookCategories{ history, // by default it is given 0 numOfBooks, // by default it is given 1 numOfShelves // by default it is given 2 } 

We can also specify the numbers in the enum:

enum meatStock{ chicken=100, mutton=20, beef // NOTICE THAT BEEF DOES NOT HAVE ANY VALUE, SO IT WILL OBTAIN THE NEXT INDEX OF THE PREVIOUSLY DEFINED VALUE, IN THIS CASE 21 } 

We can also make combinations of strings and numbers in an enum without any problems.

This defines a specific structure for an object:

interface videoRequest{ id:number, title:string, comments:string, likes:number, dislikes?:number, // The ? indicates that it can either have dislikes or not readonly username:string // This indicates that it can only be assigned when initialized }