TypeScript First Program

Writing your first program in TypeScript involves creating a .ts file, compiling it to JavaScript, and running it. This simple example demonstrates how TypeScript's type system works.

 

Steps to Create a TypeScript Program

Create a TypeScript File
Create a file named hello.ts and write the following code:

function greet(name: string): string {  
  return `Hello, ${name}!`;  
}  

const message: string = greet("TypeScript");  
console.log(message);  

Compile the TypeScript File
Use the tsc command to compile hello.ts into JavaScript:

tsc hello.ts  

This generates a file named hello.js.

Run the Compiled JavaScript
Execute the JavaScript file using Node.js:

node hello.js  

Output:

Hello, TypeScript!  

Code Explanation

• Type Annotation: The name: string and message: string ensure that the variables are of type string.
• Template Literals: Use backticks (`) to embed expressions into strings.
• Type Safety: If you pass a non-string value to greet, TypeScript will throw an error during compilation.

 

Summary

Your first TypeScript program demonstrates type annotations, type safety, and how to compile and run TypeScript code. It highlights how TypeScript improves error detection during development.