Extending moment.Duration to have a long format humanized string

moment.duration.humanizeLong.ts

import * as moment from 'moment';

declare module 'moment' {
    interface Duration {
        humanizeLong(): string;
    }
}

(moment.duration as any).fn.humanizeLong = function (): string {
    const years = this.years();
    const months = this.months();
    const days = this.days();
    const hours = this.hours();
    const minutes = this.minutes();

    const durationArray: string[] = [
        !!years ?
            years > 1 ? `${years} years` : `${years} year`
            : '',
        !!months ?
            months > 1 ? `${months} months` : `${months} month`
            : '',
        !!days ?
            days > 1 ? `${days} days` : `${days} day`
            : '',
        !!hours ?
            hours > 1 ? `${hours} hours` : `${hours} hour`
            : '',
        !!minutes ?
            minutes > 1 ? `${minutes} minutes` : `${minutes} minute`
            : ''
    ];
    return durationArray.filter(val => val !== '').join(', ');
};