The tsc Compiler

The tsc (TypeScript Compiler) is the official tool provided by TypeScript to compile .ts files into .js. Let’s go through the process of bootstrapping a simple TypeScript Node.js application and explore the features of the tsc compiler.

Step 1 - Install tsc/TypeScript Globally

To install the TypeScript compiler globally on your system, run the following command:

npm install -g typescript

Step 2 - Initialize an Empty Node.js Project with TypeScript

Set up a new Node.js project and initialize TypeScript:

mkdir node-app
cd node-app
npm init -y
npx tsc --init

These commands will:

• Create a new directory node-app
• Initialize a package.json file for your Node.js project
• Generate a tsconfig.json file, which contains the TypeScript configuration options

Step 3 - Create a a.ts File

Add a simple TypeScript file to your project:

const x: number = 1;
console.log(x);

Save this as a.ts.

Step 4 - Compile the .ts File to a .js File

Use the tsc command to compile your TypeScript code:

tsc -b

This will generate a corresponding JavaScript file a.js.

Step 5 - Explore the Generated JavaScript File

Open the newly created a.js file to observe the output. You’ll notice that:

• The TypeScript code is compiled into plain JavaScript.
• There are no TypeScript-specific constructs in the .js file.

Step 6 - Modify the Code to Introduce a Type Error

Update your a.ts file:

let x: number = 1;
x = "harkirat"; // Error: Type 'string' is not assignable to type 'number'
console.log(x);

Here, the const is changed to let, and x is assigned a string value.

Step 7 - Compile the Code Again

Run the TypeScript compiler:

tsc -b

Observe the errors in the console. Since TypeScript enforces type safety, the compilation will fail, and no updated a.js file will be generated.

Key Benefits of Using tsc

• Type Safety: Catch type errors during compile time.
• Code Integrity: Ensures a robust codebase by preventing invalid type assignments.
• Efficient Development: Reduces runtime errors by detecting issues early in the development process.

This demonstrates how the tsc compiler is a powerful tool for maintaining type safety and enhancing code reliability in TypeScript projects.