我的尝试是基于其他的答案。

function timeSince(date) {
    let minute = 60;
    let hour   = minute * 60;
    let day    = hour   * 24;
    let month  = day    * 30;
    let year   = day    * 365;

    let suffix = ' ago';

    let elapsed = Math.floor((Date.now() - date) / 1000);

    if (elapsed < minute) {
        return 'just now';
    }

    // get an array in the form of [number, string]
    let a = elapsed < hour  && [Math.floor(elapsed / minute), 'minute'] ||
            elapsed < day   && [Math.floor(elapsed / hour), 'hour']     ||
            elapsed < month && [Math.floor(elapsed / day), 'day']       ||
            elapsed < year  && [Math.floor(elapsed / month), 'month']   ||
            [Math.floor(elapsed / year), 'year'];

    // pluralise and append suffix
    return a[0] + ' ' + a[1] + (a[0] === 1 ? '' : 's') + suffix;
}

我还没有检查(虽然这并不难)，但我认为Stack Exchange站点使用jquery。Timeago插件来创建这些时间字符串。

这个插件使用起来很简单，而且很干净，还能自动更新。

下面是一个简单的例子(来自插件的主页):

First, load jQuery and the plugin: <script src="jquery.min.js" type="text/javascript"></script> <script src="jquery.timeago.js" type="text/javascript"></script> Now, let's attach it to your timestamps on DOM ready: jQuery(document).ready(function() { jQuery("abbr.timeago").timeago(); }); This will turn all abbr elements with a class of timeago and an ISO 8601 timestamp in the title: <abbr class="timeago" title="2008-07-17T09:24:17Z">July 17, 2008</abbr> into something like this: <abbr class="timeago" title="July 17, 2008">about a year ago</abbr> which yields: about a year ago. As time passes, the timestamps will automatically update.

 I achieve this by following method

   timeAgo = (date) => {
            var ms = (new Date()).getTime() - date.getTime();
            var seconds = Math.floor(ms / 1000);
            var minutes = Math.floor(seconds / 60);
        var hours = Math.floor(minutes / 60);
        var days = Math.floor(hours / 24);
        var months = Math.floor(days / 30);
        var years = Math.floor(months / 12);
    
        if (ms === 0) {
            return 'Just now';
        } if (seconds < 60) {
            return seconds + ' seconds Ago';
        } if (minutes < 60) {
            return minutes + ' minutes Ago';
        } if (hours < 24) {
            return hours + ' hours Ago';
        } if (days < 30) {
            return days + ' days Ago';
        } if (months < 12) {
            return months + ' months Ago';
        } else {
            return years + ' years Ago';
        }
    
    }
    
        console.log(timeAgo(new Date()));
        console.log(timeAgo(new Date('Jun 27 2020 10:12:19')));
        console.log(timeAgo(new Date('Jun 27 2020 00:12:19')));
        console.log(timeAgo(new Date('May 28 2020 13:12:19')));
        console.log(timeAgo(new Date('May 28 2017 13:12:19')));

function calDateAgo(dString=null){
    //var dString = "2021-04-1 12:00:00";
     
    var d1 = new Date(dString);
    var d2 = new Date();
    var t2 = d2.getTime();
    var t1 = d1.getTime();
    var d1Y = d1.getFullYear();
    var d2Y = d2.getFullYear();
    var d1M = d1.getMonth();
    var d2M = d2.getMonth();
     
    var time_obj = {};
    time_obj.year = d2.getFullYear()-d1.getFullYear();
    time_obj.month = (d2M+12*d2Y)-(d1M+12*d1Y);
    time_obj.week = parseInt((t2-t1)/(24*3600*1000*7));
    time_obj.day = parseInt((t2-t1)/(24*3600*1000));
    time_obj.hour = parseInt((t2-t1)/(3600*1000));
    time_obj.minute = parseInt((t2-t1)/(60*1000));
    time_obj.second = parseInt((t2-t1)/(1000));

    for (const obj_key in time_obj) {
        if(time_obj[obj_key] == 0){
            delete time_obj[obj_key];
        }
    }
    var ago_text = 'just now';

    if(typeof Object.keys(time_obj)[0] != 'undefined'){
        var time_key = Object.keys(time_obj)[0];
        var time_val = time_obj[Object.keys(time_obj)[0]];
        time_key += (time_val > 1) ? 's':'';
        ago_text = time_val+' '+time_key+' ago'; 
    }
    
    return ago_text;
}

简单易读版本:

const relativeTimePeriods = [
    [31536000, 'year'],
    [2419200, 'month'],
    [604800, 'week'],
    [86400, 'day'],
    [3600, 'hour'],
    [60, 'minute'],
    [1, 'second']
];

function relativeTime(date, isUtc=true) {
    if (!(date instanceof Date)) date = new Date(date * 1000);
    const seconds = (new Date() - date) / 1000;
    for (let [secondsPer, name] of relativeTimePeriods) {
        if (seconds >= secondsPer) {
            const amount = Math.floor(seconds / secondsPer);
            return `${amount} ${name}${amount ? 's' : ''}s ago`;
        }
    }
    return 'Just now';
}

我的尝试是基于其他的答案。

function timeSince(date) {
    let minute = 60;
    let hour   = minute * 60;
    let day    = hour   * 24;
    let month  = day    * 30;
    let year   = day    * 365;

    let suffix = ' ago';

    let elapsed = Math.floor((Date.now() - date) / 1000);

    if (elapsed < minute) {
        return 'just now';
    }

    // get an array in the form of [number, string]
    let a = elapsed < hour  && [Math.floor(elapsed / minute), 'minute'] ||
            elapsed < day   && [Math.floor(elapsed / hour), 'hour']     ||
            elapsed < month && [Math.floor(elapsed / day), 'day']       ||
            elapsed < year  && [Math.floor(elapsed / month), 'month']   ||
            [Math.floor(elapsed / year), 'year'];

    // pluralise and append suffix
    return a[0] + ' ' + a[1] + (a[0] === 1 ? '' : 's') + suffix;
}