Typescript references

Typescript features

Static typing - In dynamically typed languages(JavaScript, Python, PHP, Ruby…) types of variables are generally not known at compile time. In a statically typed language, variables, parameters, and objects members (i.e properties and methods) have types that the compiler knows at compile time. The compiler use that information to perform type checks and to optimize the compiled code. TypeScript introduces static types into JavaScript!
- Catch more errors at compile time (and less bugs at run time)
- It helps IDEs with code-completion (IntelliSense)
- Type annotations are useful for documentation, which helps large teams to collaborate
- Static Typing in JavaScript makes it less “ugly” for developers coming from Java, #C, and so on.
Interfaces
Decorators
Transpile into old ES versions (tsc can be uses as substitution of babel)
Many others…

Install Typescript

# Local installation
npm install typescript
npx tsc -v

# Global installation
sudo npm install typescript -g
tsc -v

Basic usage

# Convert .ts to .js
tsc src/example-1.ts

# Watch a directory...
tsc -w src/* --outDir dist/
tsc --watch src/* --outDir dist/ --target es5 # Default es3

Init TSC

cd typescript.demo.proj
mkdir {dist,src}

Create the package.json with some default settings:

npm init -y

Then update the scripts section in package.json:

"scripts": {
  "build": "tsc",
  "start": "npm run build -- -w"
},

Create the tsconfig.json with some default settings:

tsc --init

Then update the scripts section in tsconfig.json:

{
  "compilerOptions": {
    "outDir": "./dist/",
    "sourceMap": false,
    "module": "commonjs",
    "target": "es5",
  },
  "exclude": [
    "node_modules"
  ]
}