const hours = 1000 * 60 * 60;
const days = hours * 24;
const weeks = days * 7;
const UNIT_TO_NUM = { hours, days, weeks };
class Duration {
constructor(num, unit) {
this.number = num;
this.unit = unit;
}
toNumber() {
return UNIT_TO_NUM[this.unit] * this.number;
}
get ago() {
return new Date(Date.now() - this.toNumber());
}
get later() {
return new Date(Date.now() + this.toNumber());
}
}
Object.keys(UNIT_TO_NUM).forEach(unit => {
Object.defineProperty(Number.prototype, unit, {
get() {
return new Duration(this, unit);
}
});
});
console.log((2).weeks.ago)
