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event-class.js
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49 lines (41 loc) · 1.11 KB
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'use strict';
class Point {
#x;
#y;
#events;
constructor({ x, y }) {
const errors = Point.validate(x, y);
if (errors.length > 0) {
const cause = new AggregateError(errors, 'Validation');
throw new RangeError('Bad coordinates', { cause });
}
this.#x = x;
this.#y = y;
this.#events = {
move: ({ x, y }) => {
this.#x += x;
this.#y += y;
},
clone: () => new Point({ x: this.#x, y: this.#y }),
toString: () => `(${this.#x}, ${this.#y})`,
};
}
static validate(x, y) {
const errors = [];
if (!Number.isFinite(x)) errors.push(new TypeError(`Invalid x: ${x}`));
if (!Number.isFinite(y)) errors.push(new TypeError(`Invalid y: ${y}`));
return errors;
}
emit(eventName, args) {
const event = this.#events[eventName];
if (!event) throw new Error(`Unknown event: ${eventName}`);
return event(args);
}
}
// Usage
const p1 = new Point({ x: 10, y: 20 });
console.log(p1.emit('toString'));
const c1 = p1.emit('clone');
console.log(c1.emit('toString'));
c1.emit('move', { x: -5, y: 10 });
console.log(c1.emit('toString'));