Conditionally loading Munchkin on Marketo LPs (for GDPR & related policies)

I've written before about conditionally loading Munchkin based on IP ranges (which isn't a native feature), and about adding custom Munchkin options on Marketo LPs (where Munchkin is injected automatically with special options).

As Community user GF points out, anti-cookie/anti-tracking legislation like GDPR requires a combo of these earlier approaches:

  1. the end user must consent before Munchkin runs on Marketo LPs
  2. you need to preserve the LP-specific special options if they do consent
  3. you may need to add custom options, most often domainLevel

To get this working, we need to hack around Munchkin's hard-coded load-and-run logic on Marketo LPs. Luckily, it's not horrendously complex, though it'll look obscure to people inexperienced with such shenanigans.

Here are the scripts to put as high up in your page as possible (in <head> ideally, but near the top of <body> is fine too, like you get with an HTML element on a Free-Form LP):

<script type="application/javascript" 
(function munchkinInitDeferred(customOptions){
  var nativeMunchkinInit = Munchkin.init;
  Munchkin.init = function cacheInitOptions(id, options){
    if (customOptions) { 
        options[key] = customOptions[key];
    Munchkin.init = nativeMunchkinInit.bind(Munchkin, id, options);
    console.log("Munchkin: Cached options", options);
})( /* custom init options here if necessary */ );

Notice I'm not passing any args to the function in the basic usage example above, there's just a comment:

...( /* custom init options here if necessary */ )`

If you need custom Munchkin initialization options (most commonly domainLevel) then pass those in an object:

...( {domainLevel: 2, someOtherOption: true} )

What does it do?

The code works by caching the Munchkin config for later — including both Marketo's special options and your custom options — while stopping the page from immediately running Munchkin.init().

You can see the cached config in the browser console:


This gives you complete control. Once someone opts in to being tracked, then run Munchkin.init() manually (call it with no arguments, since all the arguments, including the 123-ABC-456 Munchkin ID, are already stored).

Enjoy staying legal!