google-inbox-userscript.js

/* This is a FluidApp userscript for Google Inbox for Mac. 
Includes options for total badge count and unread badge count.

1) You need the paid version of FluidApp (http://fluidapp.com/)
2) Point Fluid to https://inbox.google.com (I recommend the icon from here: https://medium.com/@chrismessina/create-an-icon-for-google-inbox-in-your-dock-ed269312e3bc)
3) Set the user-agent to Chrome
4) Go to window -> userscript and add click the plus sign under the first table (on the left). Name the item 'Inbox'.
5) In the second table (on the right) click the plus and type in "*inbox.google.com*".
6) Paste the contents of this document into the script area below that.
7) Configure badge count (for total or unread only) in the code below.
8) Refresh your FluidApp. (CMD + R)

Some Caveats:
- This doesn't update the badge unless it's looking at the inbox. 
- The workaround is to only show the badge count when the inbox tab is active, otherwise it shows '?' as a reminder on other tabs (snoozed, etc).
- No idea how well this works with more than one tab open.

TODO: Update count on item removal / read.
*/

function loadScript(url, onload) {
    var element = document.createElement('script');
    element.type = 'text/javascript';
    element.src = url;
    element.onload = onload;
    document.getElementsByTagName("head")[0].appendChild(element);
}

function onload() {
    window.fluid.dockBadge = '';
    setTimeout(updateBadge, 5000);
    setInterval(updateBadge, 10000);

    function updateBadge() {
        // Inbox title will always be the first item in the D4 Class. It's shown and unshown depending on the selected folder (snoozed, etc)
        var inboxTabSpan = document.querySelector('[jsaction="global.navigate_and_refresh"]'),
            inboxTabTitle = '',
            inboxTabStyle = 'display: none;';
        if (inboxTabSpan) {
            inboxTabTitle = inboxTabSpan.getAttribute('title');
            inboxTabStyle = inboxTabSpan.getAttribute('style');
        }

        if (inboxTabStyle === 'display: none;') {
            // Inbox hidden.
            window.fluid.dockBadge = '?';
        } else {
            //Check for Inbox Zero Sunrise Image
            var inboxZero = $('.j');
            if (inboxZero.length >= 1) {
                window.fluid.dockBadge = '';
            } else {
                // Inbox visible
                var allEmails = $('.scroll-list-item');
                var unreadEmails = allEmails.find('div:contains("Unread"):not(:has(*)):visible');

                var count = 0;

                unreadEmails.each(function ($row) {
                    
                });

                /////////////////////////////
                // allEmails.length = ALL EMAILS IN INBOX
                // OR
                // unreadEmails.length = ONLY UNREAD ITEMS IN INBOX
                var count = unreadEmails.length;
                /////////////////////////////

                if (count >= 1) {
                    window.fluid.dockBadge = count;
                } else {
                    window.fluid.dockBadge = '';
                }
            }
        }
    }
}

if (typeof window.jQuery === 'undefined') {
    loadScript('//ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js', onload);
} else {
    onload();
}

Thankyou for fixing this. Just got my invite to Inbox and bought the Fluid app based on the article that had the original. Was very sad to see it broken :(

@cooperaj oh thanks, sorry I missed your comment. Only saw it now as I've just updated this to keep it working with the latest changes :)