07-playing-with-prototypes.js

// PLAYING WITH PROTOTYPES

/* ------------------------------------------------- 
    Part 1 - extending built-ins

    Remember "makeImportant()" earlier?
    Lets add it to the String prototype, under the name "importantify".
    This lets us do the following: "hello world".importantify();
    We will need to create a new function, not taking the string as a parameter
    but instead using the value of "this"
   ------------------------------------------------- */


// Make this syntax possible:
// (5).plus(3).minus(6)
// hint: extend the Number prototype

/* ------------------------------------------------- 
    Part 2 - Constructors
    
    Create a constructor function "Warship" that creates new warship objects.
    The constructors accepts parameters name (string) and cannons (number).
    { destroyed: false, cannons: 3, name: 'HMS Belfast' }
   ------------------------------------------------- */


/*
    All warships should be able to shoot. Extend your constructor with
    a function by using "this" inside the constructor
    (this is how they shoot: () => console.log('BOOM!'))
*/


/*
    Now every warship contains its own shoot-method.
    We can improve memory consumption vastly by adding the method to the prototype instead.
    Remove the instance method and add shoot() to the prototype.
*/


test('Playing with prototypes', function() {
    equal(typeof String.prototype.importantify, 'function', 
          'String.prototype.importantify should be defined')
    equal('helloes'.importantify(), 'HELLOES!!!', 'it should also work');
    
    equal((5).plus(3).minus(4), 4, 'Basic maths');

    const ship = new Warship('HMS Belfast', 3);
    equal(typeof ship, 'object');
    equal(ship.name, 'HMS Belfast');
    equal(ship.cannons, 3);

    ok(ship.shoot)
});