问如何将日期转换为“天、小时或秒前”字符串？

EN

function conversions() {
    notif.rollupList.rollups.forEach(function (rollup) {
      rollup.type = getChangeType(rollup.type);
      rollup.modifiedAt = convertDate(rollup.modifiedAt)
    })
  }

  // Converts the date to 'something something ago'
  function convertDate(dateString) {
    var seconds = Math.floor((Date.now() - new Date(dateString)) / 
1000);
    if (seconds >= 60) {
      var minutes = Math.floor(seconds / 60);
      if (minutes >= 60) {
        var hours = Math.floor(minutes / 60);
        if (hours >= 24) {
          var days = Math.floor(hours / 24);
          if (days > 1) {
            return days.toString() + ' days ago'
          } else {
            return days.toString() + ' day ago'
          }
        } else {
          if (hours > 1) {
            return hours.toString() + ' hours ago'
          } else {
            return hours.toString() + ' hour ago'
          }
        }
      } else {
        if (minutes > 1) {
          return minutes.toString() + ' minutes ago'
        } else {
          return minutes.toString() + ' minute ago'
        }
      }
    } else {
      if (second > 1) {
        return seconds.toString() + ' seconds ago'
      } else {
        return seconds.toString() + ' second ago'
      }
    }
  }