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I have a one-pager campaign site which should collect PageView and LEAD event data for Facebook targeting with "advanced matching".

For PageView, I need to initialize the Pixel on page load. For advanced matching, I need to provide user data for initialization script — however, I only have user data available after user has submitted the data, which is when the LEAD event should be sent.

Is it possible to provide the initialization script with a "pointer" to a javascript variable that is used when sending the LEAD event? Help page hints at this, but all the examples have e.g. email parameter provided as plain text or sha256 hash; not as JS variable nor as a textual pointer to one.

From the "Advanced Matching with the Pixel" help page:

To enable this feature, modify the default FB pixel code to pass data into the pixel init call.

fbq('init', '<FB_PIXEL_ID>', { 
    em: '{{_email_}}', 
    // Data will be hashed automatically via a dedicated function in FB pixel
    ph: '{{_phone_number_}}',
    fn: '{{_first_name_}}'
    ....
})

In the example above, you will need to replace email, phone_number, first_name with the names of the variables on your website that capture this data.

Let's say I have user_email variable in the same scope as fbq-init:

var user_email = '';

Later, after the form is submitted, this variable will be populated like

user_email = "john@example.com";

How should I reference the variable in fbq? (1) Like this?

fbq('init', 123456, { em: '{{_user_email_}}' });

(2) Or like this?

fbq('init', 123456, { em: 'user_email' });

(3) Or should I provide it simply with the variable:

fbq('init', 123456, { em: user_email }); // nb: user_email === false when this is run

(4) Or should I initialize the pixel without any matching data and later enrich it? (How?)

A reputable ad agency sent me with instructions to submit the name of the variable as in my example 2, but the help page hints at 1 without actually providing any real world examples.

I tried all the options 1–3, and it seems variables won't get re-evaluated in subsequent fbq('track', …); calls after the initialization. If user_email is blank to start with, none of the events will include hashed user data.

Moreover even if I start with a valid email user_email = "john@example.com"; (also tried real domains instead of example.com) only method 3 will work — but, as expected, this is not dynamic, ie. if user_email changes the hashes won't.

It is as if there is no string-variable replacement to begin with.

Would the more proper question be: how do I submit user data for advanced matching after the pixel initialization? Instead of trying to make the initialization lazy/dynamic.

Jari Keinänen
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    (2) requires actual values to be passed, not variable names. If you want the pixel code to read it from variables, then you need to use (1). Suggest you install the pixel helper Chrome extension, that helps with debugging. – CBroe Sep 21 '16 at 08:28
  • Thanks for your help! Sadly, when I set `user_email = ''` and use `fbq('init', 1, { em: '{{_user_email_}}' });` to initialize pixel; send `PageView`; then set `user_email` to an actual email; then send `Lead`, I can see from both Pixel helper and Developer tools that *no* hashed user data is being sent with *neither* event (should be sent with `Lead`). If I set the email address manually when initializing the pixel (ie. `fbq('init', 1, {em: 'test@example.com'});` I can see the hashed email is sent with both events. – Jari Keinänen Sep 21 '16 at 10:44
  • Not sure at what point it is supposed to grab the value of that variable. Try initializing `user_email` with an email address from the beginning, before you call the init method, to see if that changes anything. – CBroe Sep 21 '16 at 10:54
  • @CBroe I tested that and included the results in the question. (Thanks again for the Pixel helper — sped up digging a lot) – Jari Keinänen Sep 21 '16 at 11:08
  • I've been having trouble asking that same question. Thank you for summing it up here so clearly. Seems crazy that this isn't possible :-/ – Digs Oct 26 '16 at 19:35
  • Searched everywhere and still no clear answer to this question which seems pretty important. In other words: can we init the pixel multiple times, every time we've got new data to improve the Advanced Matching? e.g. let's say it's inited without advanced matching, then later re-inited with `em`, and later with `ph` -- does that work? – Dan P. Jun 11 '19 at 12:37

1 Answers1

2

As a workaround it is possible to generate a Lead event with email user data by loading the pixel (image) via javascript:

// here the user email is unknown, so PageView is generated without email
fbq('init', 123456, {});
fbq('track', 'PageView');

// Later the form is submitted via ajax, so the user email is known
$.ajax(…).done(function(data) {
    // I decided to sha256 hash the email address in the backend and return it for the javascript handler
    var pixel = document.createElement('img');
    pixel.src = 'https://www.facebook.com/tr/?id=123456&ev=Lead&ud[em]=' + data;
    document.body.appendChild(pixel);
    // confirmed by the Pixel helper Chrome extension, this does generate a valid tracking event
    // (ironically, we're loading the noscript version via javascript)
});

Of course, a pure fbq version would be more desirable. Also, I'm yet unaware of possible drawbacks, should there be any.

Jari Keinänen
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