Relative date Pipe for Angular2 + TypeScript . Convert date|timestamp into relative date string e.g. "5 days ago", "1 minute ago" etc.

relative-date.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

// Epochs
const epochs: any = [
    ['year', 31536000],
    ['month', 2592000],
    ['day', 86400],
    ['hour', 3600],
    ['minute', 60],
    ['second', 1]
];

/*
 * Turn Date into realtive date (e.g. 5 days ago)
 * Usage:
 *   value | relativeDate
 * Example:
 *   {{ 86400 |  relativeDate}}
 *   formats to: '1 day ago'
*/
@Pipe({name: 'relativeDate'})
export class RelativeDatePipe implements PipeTransform {

    getDuration(timeAgoInSeconds: number) {
        for (let [name, seconds] of epochs) {
            let interval = Math.floor(timeAgoInSeconds / seconds);

            if (interval >= 1) {
                return {
                    interval: interval,
                    epoch: name
                };
            }
        }
        return {
            interval: 0,
            epoch: 'seconds'
        };
    };

    transform(dateStamp: number): string {

        let timeAgoInSeconds = Math.floor((new Date().getTime() - new Date(dateStamp).getTime()) / 1000);
        let {interval, epoch} = this.getDuration(timeAgoInSeconds);
        let suffix = interval === 1 ? '' : 's';

        return `${interval} ${epoch}${suffix} ago`;

    }

}

This is super helpful. Thanks!

this only works for in the past, so I thought I would expand on it to add future relativity

    getDuration(timeAgoInSeconds: number) {
        for (let [name, seconds] of epochs) {
            let interval = Math.floor(Math.abs(timeAgoInSeconds) / seconds);
            if (interval >= 1) {
                return {
                    interval: Math.abs(interval),
                    epoch   : name
                };
            }
        }
        return {
            interval: 0,
            epoch   : 'seconds'
        };
    };

    transform(dateStamp: number): string {
        let timeAgoInSeconds  = Math.floor((new Date().getTime() - new Date(dateStamp).getTime()) / 1000);
        let {interval, epoch} = this.getDuration(timeAgoInSeconds);
        let suffix            = interval === 1 ? '' : 's';
        let ago               = timeAgoInSeconds < 0 ? '' : ' ago';
        let _in                = timeAgoInSeconds < 0 ? 'in ' : '';

        return `${_in}${interval} ${epoch}${suffix}${ago}`;

    }