typescript.md

Typescript

Class definition

Pretty similar to java syntax, but types are provided using the ":" notation.

class Turtle {
  heading: number;
  x: number;
  y: number;
}

Constructors

Constructors are always called constructor, and access to class level fields, likewise uses the this. syntax:

constructor(heading: number, x: number, y: number) {
    this.heading = heading;
    this.x = x;
    this.y = y;
}

Secrecy

private, protected, and # (enforcing private at runtime, not just compile time) are supported. :)

Launchers

• Any typescript file can be a launcher.
• No launcher function is needed, in principle you can just write a console.log() statement, done.

Using another class

Referencing classes

By default, nothing is referenced - not even files in the same folder. To access other classes, an import and and export are needed.

• Export sample, after class end:

export { Turtle };

• Import sample, at class start:

import { Turtle } from 'Turtle'

Must be "'" characters, must not include .ts file extension.

Object creation

Using object as type is not a good idea, we have no actual type safety, and we cannot access any fields bound to the specific class.

let turtle: object = new Turtle(0, 0, 0);
console.log(turtle.heading);

heading cannot be accessed, because object does not bind to such a field.

Better: use correct type. Everything in same folder is automatically accessible:

let turtle: Turtle = new Turtle(0, 0, 0);
console.log(turtle.heading);