TypeScript

http://www.typescriptlang.org/

TypeScript offers classes, interfaces, mixins, modules, and generics to help you build robust components.

These features are available at development time for high-confidence application development, but are compiled into simple JavaScript.

TypeScript types let you define interfaces between software components and to gain insight into the behavior of existing JavaScript libraries.

Handbook: http://www.typescriptlang.org/Handbook

Install

sudo npm install -g typescript

First program

cat > inheritance.ts

class Animal {
    constructor(public name: string) { }
    move(meters: number) {
        alert(this.name + " moved " + meters + "m.");
    }
}

class Snake extends Animal {
    constructor(name: string) { super(name); }
    move() {
        alert("Slithering...");
        super.move(5);
    }
}

class Horse extends Animal {
    constructor(name: string) { super(name); }
    move() {
        alert("Galloping...");
        super.move(45);
    }
}

var sam = new Snake("Sammy the Python");
var tom: Animal = new Horse("Tommy the Palomino");

sam.move();
tom.move(34);

tsc inheritance.ts