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How to use the TypeScript compiler (tsc) to compile TypeScript code:

Here's a detailed lab worksteps guide on how to use the TypeScript compiler (tsc) to compile TypeScript code:

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Lab Worksteps Guide: Using TSC to Compile TypeScript

Objective: Learn how to set up a TypeScript project and use the TypeScript compiler (tsc) to compile TypeScript code into JavaScript.

Prerequisites: - Node.js installed on your system - Basic understanding of TypeScript syntax

Step 1: Install TypeScript Globally

1. Open your terminal or command prompt. 2. Run the following command to install TypeScript globally: ``` npm install -g typescript ``` 3. Verify the installation by checking the TypeScript version: ``` tsc --version ```

Step 2: Create a New TypeScript Project

1. Create a new directory for your project: ``` mkdir ts-compile-demo cd ts-compile-demo ``` 2. Initialize a new Node.js project: ``` npm init -y ``` 3. Install TypeScript as a dev dependency in your project: ``` npm install --save-dev typescript ```

Step 3: Configure TypeScript

1. Create a TypeScript configuration file (tsconfig.json): ``` npx tsc --init ``` 2. Open tsconfig.json in your text editor and make sure the following options are set: ```json { "compilerOptions": { "target": "es6", "module": "commonjs", "outDir": "./dist", "rootDir": "./src", "strict": true } } ```

Step 4: Create TypeScript Files

1. Create a src directory: ``` mkdir src ``` 2. Create a TypeScript file named app.ts in the src directory: ``` touch src/app.ts ``` 3. Add some TypeScript code to app.ts: ```typescript function greet(name: string): string { return `Hello, ${name}!`; }

console.log(greet("TypeScript")); ```

Step 5: Compile TypeScript Using TSC

1. Compile your TypeScript code: ``` npx tsc ``` 2. Verify that a dist directory has been created with app.js inside.

Step 6: Run the Compiled JavaScript

1. Run the compiled JavaScript file: ``` node dist/app.js ``` 2. You should see the output: "Hello, TypeScript!"

Step 7: Watch Mode

1. Use tsc's watch mode to automatically recompile on file changes: ``` npx tsc --watch ``` 2. Make changes to src/app.ts and observe that tsc automatically recompiles the code.

Step 8: Compile Multiple Files

1. Create another TypeScript file named utils.ts in the src directory: ``` touch src/utils.ts ``` 2. Add some code to utils.ts: ```typescript export function capitalize(str: string): string { return str.charAt(0).toUpperCase() + str.slice(1); } ``` 3. Update app.ts to use the new utility function: ```typescript import { capitalize } from './utils';

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

console.log(greet("typescript")); ``` 4. Compile the project: ``` npx tsc ``` 5. Run the compiled JavaScript: ``` node dist/app.js ``` 6. You should see the output: "Hello, Typescript!"

Step 9: Use TSC with npm scripts

1. Open package.json and add the following scripts: ```json "scripts": { "build": "tsc", "start": "node dist/app.js", "dev": "tsc --watch" } ``` 2. Now you can use npm to run these scripts: - To compile: `npm run build` - To run the compiled code: `npm start` - To start watch mode: `npm run dev`

Conclusion:

You've now learned how to set up a TypeScript project, use tsc to compile TypeScript code, work with multiple files, and integrate tsc into your npm scripts.

This workflow forms the foundation for developing larger TypeScript applications.

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