Appends the Number prototype with date related functions

number-date-extensions.js

/*
 * let a = 1;
 * let an = 1;
 * let some = 2;
 *
 * Currently supports:
 * - a.day.ago
 * - some.days.ago
 * - a.week.ago
 * - some.weeks.ago
 * - a.month.ago
 * - some.months.ago
 * - a.year.ago
 * - some.years.ago
 * - a.decade.ago
 * - some.decades.ago
 * - a.centry.ago
 * - some.centuries.ago
 * - a.millennium.ago
 * - some.millennia.ago
 * - some.millenniums.ago
 * - an.age.ago
 * - some.ages.ago
 *
 * - a.day.ago
 * - a.day.in.the.past
 * - a.day.from.now
 * - a.day.in.the.future
 * - a.day.before(date) // where date is any parameters that creating a Date would take
 * - a.day.after(date) // where date is any parameters that creating a Date would take
 */

class Period {
  value;
  func;

  constructor({
    value,
    func,
  }) {
    this.value = value;
    this.func = func;
  }

  get in() {
    let obj = this;
    
    return {
      the: {
        get future() {
          return obj.after(new Date());
        },

        get past() {
          return obj.ago;
        },
      },
    }
  }

  get from() {
    let obj = this;
    
    return {
      get now() {
        return obj.after(new Date());
      },
    };
  }

  get ago(){
    return this.before(new Date());
  }
  
  before(...args) {
    let date = new Date(...args);
    date[`set${this.func}`](date[`get${this.func}`]() - this.value);
    return date;
  }

  after(...args) {
    let date = new Date(...args);
    date[`set${this.func}`](date[`get${this.func}`]() + this.value);
    return date;
  }
}

Object.defineProperties(Number.prototype, {
  days: {
    get() {
      return new Period({
        value: this,
        func: 'Date',
      });
    },
  },

  day: {
    get() {
      return this.days;
    },
  },

  weeks: {
    get() {
      return (this * 7).days;
    },
  },

  week: {
    get() {
      return this.weeks;
    },
  },

  months: {
    get() {
      return new Period({
        value: this,
        func: 'Month',
      });
    },
  },

  month: {
    get() {
      return this.months;
    },
  },

  years: {
    get() {
      return new Period({
        value: this,
        func: 'FullYear',
      });
    },
  },

  year: {
    get() {
      return this.years;
    },
  },

  decades: {
    get() {
      return (this * 10).years;
    },
  },

  decade: {
    get() {
      return this.decades;
    },
  },

  centuries: {
    get() {
      return (this * 100).years;
    },
  },

  century: {
    get() {
      return this.centuries;
    },
  },

  millennia: {
    get() {
      return (this * 1000).years;
    },
  },

  millenniums: {
    get() {
      return this.millennia;
    },
  },

  millennium: {
    get() {
      return this.millennia;
    },
  },

  ages: {
    get() {
      return (this * 2160).years;
    },
  },

  age: {
    get() {
      return this.ages;
    },
  },
});