TypeScript Getting Started
TypeScript Compiler
TypeScript is transpiled into JavaScript using a compiler.
TypeScript being converted into JavaScript means it runs anywhere that JavaScript runs!
Installing the Compiler
TypeScript has an official compiler which can be installed through npm.
Learn more about npm, and how to get started here: What is npm?
Within your npm project, run the following command to install the compiler:
npm install typescript --save-dev
Which should give you an output similar to:
added 1 package, and audited 2 packages in 2s
found 0 vulnerabilities
The compiler is installed in the node_modules directory and can be run with: npx tsc.
npx tsc
Which should give you an output similar to:
Version 4.5.5
tsc: The TypeScript Compiler - Version 4.5.5
Followed by a list of all the Common Commands.
Configuring the compiler
By default the TypeScript compiler will print a help message when run in an empty project.
The compiler can be configured using a tsconfig.json file.
You can have TypeScript create tsconfig.json with the recommended settings with:
npx tsc --init
Which should give you an output similar to:
Created a new tsconfig.json with:
TS
target: es2016
module: commonjs
strict: true
esModuleInterop: true
skipLibCheck: true
forceConsistentCasingInFileNames: true
You can learn more at TypeScript Config
Here is an example of more things you could add to the tsconfig.json file:
{
"include": ["src"],
"compilerOptions": {
"outDir": "./build"
}
}
You can open the file in an editor to add those options.
This will configure the TypeScript compiler to transpile TypeScript files located in the src/ directory of your project, into JavaScript files in the build/ directory.
Your First TypeScript Program
Let's create a simple "Hello, World!" program to verify your TypeScript setup.
- Create a new file named
hello.tswith the following content:
hello.ts
function greet(name: string): string {
return `Hello, ${name}!`;
}
const message: string = greet("World");
console.log(message);
- Compile your TypeScript code:
npx tsc hello.ts
This will generate a hello.js file in the same directory:
function greet(name) {
return "Hello, ".concat(name, "!");
}
const message = greet("World");
console.log(message);
- Run the compiled JavaScript:
node hello.js
You should see the output:
Hello, World!
Note: If you're using the tsconfig.json configuration mentioned earlier, you would place your TypeScript files in the src directory and the compiled JavaScript will appear in the build directory.
