User:Ilmari Karonen/watchsince.js

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Documentation for this user script can be added at User:Ilmari Karonen/watchsince.

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// WATCHLIST SINCE LINK:
$(function () {
    if (!mw.config.get('wgCanonicalSpecialPageName') || mw.config.get('wgCanonicalSpecialPageName') != "Watchlist") return;
    var i = 0;
    while (i < document.forms.length && !document.forms[i].namespace) i++;
    if (i >= document.forms.length) return;

    var link = document.createElement('a');
    link.id = 'listSince';
    link.href = '#listSince';  // must have a href to show as link!

    var then = +(new Date());
    var fixLinkHref = function () {
        var url = window.location.href.split('#')[0];
        var days = ( +(new Date()) - then )/(1000 * 3600 * 24);
        if (url.match(/[?&]days=/))
            this.href = url.replace(/([?&]days=)[^&]*/, '$1'+days);
        else
            this.href = url + (url.indexOf('?') < 0 ? '?':'&') + 'days=' + days;
        return true;
    };
    link.onclick = fixLinkHref;
    link.onmousedown = fixLinkHref;  // react to middle clicks too

    var frag = document.createDocumentFragment();
    frag.appendChild(document.createTextNode(' | '));
    frag.appendChild(link);
    link.appendChild(document.createTextNode('Changes'));
    frag.appendChild(document.createTextNode(' since last load.'));

    // just one little ID attribute would be _so_ nice...
    var nsSelectForm = document.getElementsByTagName('form')[i];
    nsSelectForm.parentNode.insertBefore(frag, nsSelectForm);
});