1. commands
- npm install -g typescript // install typescript
- tsc index.ts // compile .ts to .js
- tsc // compile all src files in the src folder specified in tsconfig.json
- tsc --init // create tsconfig.json
2. tsconfig.json
- 'sourcemap' // enable debugging
3. tuple
- a new type in typescript to store data in an unchanging array
- can have different types of data
4. debug in intellij
- use 'ts-node' // no need to explicitly compile typescript to javascript, see ref 2 app
- compile & debug // explicitly compile first (manual or script in package.json)
- there's a typescript widget at the bottom of intellij, where you can compile
5. file extensions
- .ts // source code
- .d.ts // declaration file
- .tsx // contain jsx syntax
- .jsx // allow html syntax within javascript code
6. type predicate
- argumentName is Type
- always attached to a function that takes a single argument and returns a boolean
interface Cat {
numberOfLives: number;
}
interface Dog {
isAGoodBoy: boolean;
}
function isCat(animal: Cat | Dog): animal is Cat {
return typeof animal.numberOfLives === 'number';
}
7. interface
- type alias
8. generic
function removeFirstOrder<T>(arr: Array<T>): Array<T> {
arr.shift()
return arr
}
removeFirstOrders([1, 2, 3, 4])
removeFirstOrders(['a', 'b', 'c', 'd'])
reference
