Userscript to display Buyee Yahoo! Auction pages in the user's local timezone

buyee_timezone.user.js

// ==UserScript==
// @name         Buyee Yahoo Auction Timezone Converter
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Convert Yahoo! Auction timestamps on Buyee to local timezone
// @author       Brian McSweeney
// @match        https://buyee.jp/item/yahoo/auction/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=buyee.jp
// @grant        none
// @require      https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js
// @require      https://momentjs.com/downloads/moment.min.js
// @require      https://momentjs.com/downloads/moment-timezone-with-data.min.js
// ==/UserScript==
/* global $ */
/* global moment */

(function() {
    'use strict';

    var timeElements = $("ul#itemDetail_data > li:contains('(JST)')")

    // moment.js conversion testing
    // moment.tz('1 Oct 2023 23:20:19', 'D MMM YYYY HH:mm:ss', 'Asia/Tokyo').tz(moment.tz.guess()).format('D MMM YYYY HH:mm:ss')

    // Get user timezone
    const zone = moment.tz.guess()

    // Output format - https://momentjs.com/docs/#/displaying/format/
    const timeFormat = 'ddd, MMM Do - h:mm:ss A'

    // Regex to find the time string in the innerhtml
    const timeRegex = /\d\d? [A-Z][a-z]{2} \d{4} \d\d?:\d\d:\d\d/g

    // Update the displayed time and zone
    for (var i in timeElements.toArray()) {
        var timeString = timeElements[i].innerHTML.match(timeRegex)[0]
        var abbrString = moment.tz(timeString, 'D MMM YYYY HH:mm:ss', 'Asia/Tokyo').tz(zone).format('(z)')
        timeElements[i].innerHTML = timeElements[i].innerHTML.replace('(JST)', abbrString)

        var localTimeString = moment.tz(timeString, 'D MMM YYYY HH:mm:ss', 'Asia/Tokyo').tz(zone).format(timeFormat)
        timeElements[i].innerHTML = timeElements[i].innerHTML.replace(timeString, localTimeString)
    }
})();