Bookmarklet that lets you apply arbitrary google fonts to jQuery selectors.

fontswitcher.js

var bkmkltFontChooser = function () {
    return {
        v: "1.10.2",
        jQueryDone: false,
        webfontDone: false,
        fontChooserLoaded: false,
        loadjQuery: function () {
            if (window.jQuery === undefined || window.jQuery.fn.jquery < bkmkltFontChooser.v) {
                console.log("Loading jQuery");
                var script = document.createElement("script");
                script.src = ('https:' === document.location.protocol ? 'https' : 'http') +
                    "://ajax.googleapis.com/ajax/libs/jquery/" + bkmkltFontChooser.v + "/jquery.min.js";
                script.onload = script.onreadystatechange = function () {
                    if (!bkmkltFontChooser.jQueryDone && (!this.readyState || this.readyState === "loaded" || this.readyState === "complete")) {
                        bkmkltFontChooser.jQueryDone = true;
                    }
                };
                document.getElementsByTagName("head")[0].appendChild(script);
            } else {
                bkmkltFontChooser.jQueryDone = true;
            }
        },
        loadWebFont: function () {
            if (window.WebFont === undefined) {
                console.log("Loading Webfont");
                var wf = document.createElement('script');
                wf.src = ('https:' === document.location.protocol ? 'https' : 'http') +
                    '://ajax.googleapis.com/ajax/libs/webfont/1.4.7/webfont.js';
                wf.type = 'text/javascript';
                wf.onload = wf.onreadystatechange = function () {
                    if (!bkmkltFontChooser.webfontDone && (!this.readyState || this.readyState === "loaded" || this.readyState === "complete")) {
                        bkmkltFontChooser.webfontDone = true;
                    }
                };
                document.getElementsByTagName("head")[0].appendChild(wf);
            } else {
                bkmkltFontChooser.webfontDone = true;
            }
        },
        waitForLibs: function () {
            if (!bkmkltFontChooser.jQueryDone || !bkmkltFontChooser.webfontDone) {
                console.log("Spin " + bkmkltFontChooser.jQueryDone + " " + bkmkltFontChooser.webfontDone);
                setTimeout(bkmkltFontChooser.waitForLibs, 200);
            } else {
                bkmkltFontChooser.initfontChooser();
            }
        },
        firstTimeInit: function () {
            bkmkltFontChooser.loadjQuery();
            bkmkltFontChooser.loadWebFont();
            bkmkltFontChooser.waitForLibs();
        },
        setFont: function () {
            var fontname = jQuery("#bkmkltFontChooser-fontname").val();
            var selector = jQuery("#bkmkltFontChooser-selector").val();
            console.log("Applying font "+fontname+" to "+selector);
            if (fontname) {
                WebFont.load({
                    google: {
                        families: [fontname]
                    }
                });
                if (selector) {
                    jQuery(selector).css('font-family', fontname);
                }
            }
        },
        initfontChooser: function () {
            console.log("Gogogo");
            window.fontChooserloaded = true;
            if (jQuery("#bkmkltFontChooser").length === 0) {
                jQuery("body").append("<style>#bkmkltFontChooser * {font-family: sans-serif; vertical-align: baseline; margin: 0; padding: 0; color: #000; height: auto; width: auto; line-height: normal; text-align: left;}#bkmkltFontChooser{z-index:9999999999; font-size: 12px !important; background-color:#eee;position:absolute; display:none; width: 200px; top:0; left:0;padding:5px;}#bkmkltFontChooser label{margin: 5px 0;}#bkmkltFontChooser input{border:1px solid black; border-radius:0; padding: 2px;}#bkmkltFontChooser p{margin: 5px 0;}#bkmkltFontChooser a{color: #000; float:right;}#bkmkltFontChooser a:hover{text-decoration:none;}</style>");
                jQuery("body").append('<div id="bkmkltFontChooser"><form><p><label for="bkmkltFontChooser-fontname">Font Name: <input id="bkmkltFontChooser-fontname" type="text"></label></p><p><label for="bkmkltFontChooser-selector">DOM Selector: <input id="bkmkltFontChooser-selector" type="text"></label></p><p><button type="button" onclick="bkmkltFontChooser.setFont(); return false;">Go!</button><a href="javascript:jQuery("#bkmkltFontChooser").hide();">×</a></p></form></div>');
            }
            jQuery("#bkmkltFontChooser-selector").val("");
            jQuery("#bkmkltFontChooser-fontname").val("");
            jQuery("#bkmkltFontChooser").show();
            jQuery("#bkmkltFontChooser-fontname").focus();
        }
    };
}();

(function () {
    bkmkltFontChooser.firstTimeInit();
})();