TypeScript Classes

class User { # define class
    name: string;
    age: number;
    
    constructor(name: string, age: number) {
        this.name = name;
        this.age = age;
    }
}

class User {
    public name: string; # accessible everywhere (default)
    private password: string; # only in class
    protected email: string; # in class and subclasses
}

class User {
    constructor(
        public name: string, # auto-assign properties
        private age: number
    ) { }
}

class User {
    readonly id: number; # cannot be changed after init
    
    constructor(id: number) {
        this.id = id;
    }
}

class Person {
    constructor(public name: string) { }
}
class Employee extends Person { # extend class
    constructor(name: string, public id: number) {
        super(name); # call parent constructor
    }
}

abstract class Shape { # cannot be instantiated
    abstract area(): number; # must be implemented
}
class Circle extends Shape {
    area() { return 0; }
}