JSFiddle - React, Tailwind, and code Playground

HTML

<div id="time"></div>

JavaScript

setInterval('relativeTime()', 1000);

    function relativeTime()
    {
        $('#time').append(timeSince('2015-09-17 14:59:10'));
    }


    function timeSince(date) {
        if (typeof date !== 'object') {
            date = new Date(date);
        }

        var seconds = Math.floor((new Date() - date) / 1000);
        var intervalType;

        var interval = Math.floor(seconds / 31536000);
        if (interval >= 1) {
            intervalType = 'year';
        } else {
            interval = Math.floor(seconds / 2592000);
            if (interval >= 1) {
                intervalType = 'month';
            } else {
                interval = Math.floor(seconds / 86400);
                if (interval >= 1) {
                    intervalType = 'day';
                } else {
                    interval = Math.floor(seconds / 3600);
                    if (interval >= 1) {
                        intervalType = "hour";
                    } else {
                        interval = Math.floor(seconds / 60);
                        if (interval >= 1) {
                            intervalType = "minute";
                        } else {
                            interval = seconds;
                            intervalType = "second";
                        }
                    }
                }
            }
        }

        if (interval > 1 || interval === 0) {
            intervalType += 's';
        }

        return interval + ' ' + intervalType;
    };