Add ability to pass a referrer to Snowplow from an IFRAME

[alexanderdean]

Original issue: snowplow/snowplow#265
Author: https://github.com/joshspivey

There needs to be a way to pass a referrer through a iframe. Lets say you have iframe hosted at A and and host B loads the iframe you cant access the referrer it completely errors out omniture gives you the ability to set this. Now the best way to pass the referrer through is a query string on the iframe this is the less error prone method with less code and most cross browser.

Example:

<iframe src="//:locationA? referrer =http://somesite.com"></iframe> 

A solution in the Snowplow JavaScript Tracker is:

 window.qs = (function(a) {
    if (a == "") return {};
    var b = {};
    for (var i = 0; i < a.length; ++i)
    {
        var p=a[i].split('=');
        if (p.length != 2) continue;
        b[p[0]] = decodeURIComponent(p[1].replace(/\+/g, " "));
    }
    return b;
    })(window.location.search.substr(1).split('&'));


SnowPlow.getReferrer = function() {
    var a = "";
    if (window.qs["referrer"]) {
              a=window.qs["referrer"];
    } else {
        try {
            a = SnowPlow.windowAlias.top.document.referrer
        } catch (c) {
            if (SnowPlow.windowAlias.parent) {
                try {
                    a = SnowPlow.windowAlias.parent.document.referrer
                } catch (b) {
                    a = ""
                }
            }
        }
    }

[alexanderdean]

Hey joshspivey - agreed, it would be very cool to have a way of still passing the referer back to Snowplow when within an iframe.

Many thanks for sharing that code. To get this added into the JavaScript tracker, please:

1. Sign one of our two CLAs - https://github.com/snowplow/snowplow/wiki/CLA
2. Create a fork of the Snowplow project
3. Add the above code into it, plus any additional wiring code you need
4. Smoke-test it to check that it works as you expect
5. Submit a pull request back to this project, including a quick overview of the new functionality - for example, it's not obvious to me what best practice is for how to set the ?referrer= in the iframe's querystring

Many thanks - let me know if you have any questions!

[alexanderdean]

Done in 0.14.0, closing.