phn-switcher.js

function phnInjectMultiStyleHeader() {
    if (document.getElementById('phn-multi-style-header')) {
        return;
    }

    const HEAD = document.getElementsByTagName('head')[0];
    const STYLE = HEAD.appendChild(document.createElement('style'));

    STYLE.setAttribute('id', 'phn-multi-stye-header');

    STYLE.innerHTML = "" +
        "body.phn-white-theme," +
        ".phn-white-theme blockquote cite," +
        ".phn-white-theme blockquote small," +
        ".phn-white-theme .main-navigation a," +
        ".phn-white-theme .menu-toggle," +
        ".phn-white-theme .dropdown-toggle," +
        ".phn-white-theme .social-navigation a," +
        ".phn-white-theme .post-navigation a," +
        ".phn-white-theme .pagination a:hover," +
        ".phn-white-theme .pagination a:focus," +
        ".phn-white-theme .widget-title a," +
        ".phn-white-theme .site-branding .site-title a," +
        ".phn-white-theme .entry-title a," +
        ".phn-white-theme .page-links > .page-links-title," +
        ".phn-white-theme .comment-author," +
        ".phn-white-theme .comment-reply-title small a:hover," +
        ".phn-white-theme .comment-reply-title small a:focus {" +
        "color: black;" +
        "}" +
        ".phn-white-theme .site {" +
        "background-color: white;" +
        "}" +
        "body.phn-white-theme.custom-background {" +
        "background-color: white;" +
        "}" +
        ".phn-white-theme blockquote," +
        ".phn-white-theme .post-password-form label," +
        ".phn-white-theme a:hover, a:focus, a:active," +
        ".phn-white-theme .post-navigation .meta-nav," +
        ".phn-white-theme .image-navigation," +
        ".phn-white-theme .comment-navigation," +
        ".phn-white-theme .widget_recent_entries" +
        ".phn-white-theme .post-date," +
        ".phn-white-theme .widget_rss" +
        ".phn-white-theme .rss-date," +
        ".phn-white-theme .widget_rss cite," +
        ".phn-white-theme .site-description," +
        ".phn-white-theme .author-bio," +
        ".phn-white-theme .entry-footer," +
        ".phn-white-theme .entry-footer a," +
        ".phn-white-theme .sticky-post," +
        ".phn-white-theme .taxonomy-description," +
        ".phn-white-theme .entry-caption," +
        ".phn-white-theme .comment-metadata," +
        ".phn-white-theme .pingback .edit-link," +
        ".phn-white-theme .comment-metadata a," +
        ".phn-white-theme .pingback .comment-edit-link," +
        ".phn-white-theme .comment-form label," +
        ".phn-white-theme .comment-notes," +
        ".phn-white-theme .comment-awaiting-moderation," +
        ".phn-white-theme .logged-in-as," +
        ".phn-white-theme .form-allowed-tags," +
        ".phn-white-theme .site-info," +
        ".phn-white-theme .site-info a," +
        ".phn-white-theme .wp-caption .wp-caption-text," +
        ".phn-white-theme .gallery-caption," +
        ".phn-white-theme .widecolumn label," +
        ".phn-white-theme .widecolumn .mu_register label {" +
        "color: #404040;" +
        "}" +
        "body:not(.custom-background-image):before { display: none }" +
        "#phn-theme-toggle {" +
        "position: absolute;" +
        "top: 0px;" +
        "right: 0px;" +
        "cursor: pointer;" +
        "width: 30px;" +
        "height: 30px;" +
        "text-align: center;" +
        "line-height: 30px;" +
        "background-color: #333;" +
        "color: #111;" +
        "font-size: 18px;" +
        "font-weight: bold;" +
        "user-select: none;" +
        "}" +
        "#phn-theme-toggle:hover {" +
        "background-color: white;" +
        "color: black;" +
        "}" +
        ".phn-white-theme #phn-theme-toggle {" +
        "background-color: #ddd;" +
        "color: white;" +
        "}" +
        ".phn-white-theme #phn-theme-toggle:hover {" +
        "background-color: black;" +
        "color: white;" +
        "}";
}

function phnSetWhiteTheme() {
    var BODY = document.getElementsByTagName('body')[0];
    BODY.className = BODY.className + ' phn-white-theme';

    if (window.localStorage) {
        window.localStorage.setItem('phn-theme', 'white');
    }
}

function phnUnsetWhiteTheme() {
    var BODY = document.getElementsByTagName('body')[0];
    BODY.className = BODY.className.replace(' phn-white-theme', '');

    if (window.localStorage) {
        window.localStorage.removeItem('phn-theme');
    }
}

function phnToggleTheme() {
    if (document.getElementsByTagName('body')[0].className.indexOf('phn-white-theme') >= 0) {
        phnUnsetWhiteTheme();
    } else {
        phnSetWhiteTheme();
    }
}

function phnInjectTheme() {
    phnInjectMultiStyleHeader();

    if (document.getElementById('phn-theme-toggle')) {
        return;
    }

    const BODY = document.getElementsByTagName('body')[0];
    const TOGGLE = BODY.appendChild(document.createElement('a'));

    TOGGLE.setAttribute('id', 'phn-theme-toggle')
    TOGGLE.innerHTML = 'A';

    document.getElementById('phn-theme-toggle').addEventListener('click', function (e) {
        e.preventDefault();
        phnToggleTheme();
    });
}

function phnOnLoad() {
    phnInjectTheme();

    if (window.localStorage) {
        if (window.localStorage.getItem('phn-theme') === 'white') {
            phnSetWhiteTheme();
        }
    }
}

phnOnLoad();