Note: After saving, you have to bypass your browser's cache to see the changes. Google Chrome, Firefox, Microsoft Edge and Safari: Hold down the ⇧ Shift key and click the Reload toolbar button. For details and instructions about other browsers, see Wikipedia:Bypass your cache.
$.when( mw.loader.using(['mediawiki.util','mediawiki.api']), $.ready).done( function () {
    if (mw.config.get("wgNamespaceNumber") % 2 == 0 && mw.config.get("wgNamespaceNumber") != 4)
        // not a talk page and not project namespace
        return;
    if (mw.config.get("wgNamespaceNumber") == -1)
        // is a special page
        return;
    $("head").append("<style>a.arkylink { font-weight:bold } .arkyhighlight { background-color:#D9E9FF }</style>");
    var validSections = new Object();
    var fromTos = new Object();
    var wikiText = "";
    var revStamp;
    var startArchiveButton = mw.util.addPortletLink("p-cactions", "#", "ØCA", "pt-oeca", "Enter/exit the archival process", null, null);
    var overlay = $(document.createElement("button"));
    $(startArchiveButton).click(function(e) {
        $(".arkylink").click();
        $(".arky").toggle();
        $("#archivebutton").toggle();
    });
    overlay.html("archive all the selected threads")
        .attr("id", 'archivebutton')
        .css("position", 'sticky')
        .css("bottom", 0)
        .css("width", '100%')
        .css("font-size", '200%');
    $(document.body).append(overlay);
    overlay.toggle();
    overlay.click(function(e) {
        var numOfThreads, archiveTarget;
        var sections, archiveThis;
        var cutOffset, revisedPage;
        function cut(s, start, end) {
            return s.substr(0, start)   s.substring(end);
        }
        cutOffset = numOfThreads = 0;
        revisedPage = wikiText;
        sections = $("a.arkylink").map(function() {
            return $(this).attr("data-section");
        });
        if (!(numOfThreads = sections.length))
            return alert("No threads selected, aborting");
        archiveTarget = prompt("Archiving "   numOfThreads   " threads: where should we move them to? (e.g. Wikipedia:Sandbox/Archive 1)", mw.config.get("wgPageName"));
        if (!archiveTarget || archiveTarget == mw.config.get("wgPageName"))
            return alert("No archive target selected, aborting");
        sections.each(function(i, n) {
            revisedPage = cut(
                    revisedPage,
                    fromTos[n][0] - cutOffset,
                    fromTos[n][1] - cutOffset
            );
            cutOffset  = fromTos[n][1] - fromTos[n][0];
        });
        archiveThis = sections.map(function() {
            return wikiText.substring(fromTos[this][0], fromTos[this][1]);
        }).toArray().join("");
        console.log("archive this:"   archiveThis);
        console.log("revised page:"   revisedPage);
        if (1) new mw.Api().postWithToken("csrf", {action: 'edit', title: mw.config.get("wgPageName"), text: revisedPage, summary: "Removed "   numOfThreads   " threads to [["   archiveTarget   "]]", basetimestamp: revStamp, starttimestamp: revStamp})
            .done(function(res1) {
                alert("Successfully removed threads from talk page");
                console.log(res1);
                new mw.Api().postWithToken("csrf", {action: 'edit', title: archiveTarget, appendtext: "\n"   archiveThis, summary: "Added threads from [["   mw.config.get("wgPageName")   "]]"})
                    .done(function(res2) {
                        alert("Successfully added threads to archive page");
                    })
                    .fail(function(res2) {
                        alert("failed to add threads to archive page. manual inspection needed.");
                    })
                    .always(function(res2) {
                        console.log(res2);
                        window.location.reload();
                    });
            })
            .fail(function(res1) {
                alert("failed to remove threads from talk page. aborting archive process.");
                console.log(res1);
                window.location.reload();
            });
    });
    new mw.Api().get({action: 'parse', page: mw.config.get("wgPageName")}).done(function(dataShit) {
        new mw.Api().get({action: 'query', pageids: mw.config.get("wgArticleId"), prop: ['revisions'], rvprop: ['content', 'timestamp']}).done(function(shit) {
            var rv;
            rv = shit.query.pages[mw.config.get("wgArticleId")].revisions[0];
            wikiText = rv["*"];
            revStamp = rv['timestamp'];
        });
        $(dataShit.parse.sections)
            .filter(function(i, s) { return s.index == parseInt(s.index) })
            .each(function(i, s) { validSections[s.index] = s });
        for (var i in validSections) {
            i = parseInt(i);
            fromTos[i] = [
                validSections[i].byteoffset,
                validSections.hasOwnProperty(i 1)?validSections[i 1].byteoffset:Infinity
            ];
        }
        $("#mw-content-text").find(":header").find("span.mw-headline").each(function(i, title) {
            var header, headerNum, editSection, sectionNumber;
            header = $(this).parent();
            headerNum = header.prop("tagName").substr(1, 1) * 1; // wtf javascript
            editSection = header.find(".mw-editsection"); // 1st child
            sectionNumber = header.find(".mw-editsection a:last");
            if (sectionNumber[0]) {
               // Note: href may not be set.
                sectionNumber = sectionNumber.attr("href") && sectionNumber.attr("href").match(/&section=(\d )/);
                if (sectionNumber)
                    sectionNumber = sectionNumber[1];
            } else // eg <h2>not a real section</h2>
                sectionNumber = undefined;
            if (validSections.hasOwnProperty(sectionNumber))
                editSection[0].innerHTML  = "&nbsp;<span class=arky style=display:none><span class=mw-editsection-bracket>[</span><a data-header="   headerNum   " "   "data-section="   sectionNumber   " "   "onclick='$(this).closest(\":header\").toggleClass(\"arkyhighlight\");$(this).toggleClass(\"arkylink\");var archivable = $(\".arky a\"); for(var i=archivable.index(this); i<archivable.length;   i) { if (archivable[i] == this) { continue; } if ($(archivable[i]).attr(\"data-header\") > "   headerNum   " && $(archivable[i]).hasClass(\"arkylink\") != $(this).hasClass(\"arkylink\")) { $(archivable[i]).click(); } else { break; } }'>archive</a><span class=mw-editsection-bracket>]</span></span>";
        });
    });
});