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4-js-callbacks.js
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79 lines (66 loc) · 1.65 KB
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'use strict';
// Elements to be visited
class Product {
constructor(name, price) {
this.name = name;
this.price = price;
}
accept(visit) {
const inStock = true;
visit(inStock); // Just a stub
}
}
const SUNDAY = 0;
const SATURDAY = 6;
class Service {
constructor(name) {
this.name = name;
}
accept(visit) {
const day = new Date().getDay();
const available = day > SUNDAY && day < SATURDAY;
visit(available);
}
}
// Visitors to be acceped
class Purchase {
constructor(items, delivery) {
this.items = [];
items.forEach((item) => {
const visit = (available) => {
const status = `${available ? '' : 'not '}available`;
console.log(`Product "${item.name}" is ${status}`);
this.items.push(item);
};
item.accept(visit);
});
const visit = (available) => {
const status = `${available ? '' : 'not '}available`;
console.log(`Service "Delivery" is ${status}`);
this.delivery = available ? delivery : null;
};
delivery.accept(visit);
}
}
class Inspection {
constructor(items) {
this.items = [...items];
}
check() {
this.items.forEach((item) => {
const visit = (available) => {
const status = `${available ? 'in' : 'out of'} stock`;
console.log(`Product "${item.name}" is ${status}`);
};
item.accept(visit);
});
}
}
// Usage
const p1 = new Product('Laptop', 1500);
const p2 = new Product('Keyboard', 100);
const delivery = new Service('Delivery');
const electronics = new Purchase([p1, p2], delivery);
console.dir({ electronics });
const inspection = new Inspection([p1, p2]);
inspection.check();