Boomerang Howto #5: Request/page tagging

See use case #5 for a description of this requirement.

There will be several occassions when you need to add more information to the beacon that's sent back to the server. For example, you may want to tag the beacon with a page_id or you may want to do A/B testing and tag the beacon with a parameter specifying which bucket this beacon is for. You can achieve all this using the BOOMR.addVar() method.

Before you use this method, remember that each plugin adds its own parameters and you shouldn't overwrite these with your own values. See Howto #0 for a list of parameters set by boomerang's built-in plugins. Other plugins may add their own parameters, consult the documentation of the plugin to find out what these are.

BOOMR.addVar("page_id", 123);

The parameter name must be a string. We recommend only using alphanumeric characters and underscores, but you can really use anything you like. Parameter values may only be numbers or strings, ie, something that you can put into a URL.

If you need to set multiple parameters, you can pass in an object instead:

BOOMR.addVar({
		"bucket": "test#1",
		"page_id": 123
	});

Make sure you've included boomerang.js before calling BOOMR.addVar().

The beacon

The beacon will include all variables that you add in the URL. Both keys and values will be URI encoded. Your back end application will need to understand the passed in parameters.

http://yoursite.com/path/to/beacon.php?bucket=test%231&page_id=123&t_done=.....

Removing variables

You can also remove a parameter that you've added (or that a plugin has added) from the beacon. To do this, call the BOOMR.removeVar() method. This method takes in a list of name, and removes all of them from the parameter list. Any name that isn't in the parameter list is ignored.

// don't send the stooges to the server   
BOOMR.removeVar("larry", "moe", "curly");

Stopping the beacon

You can also this as a crude way to prevent the beacon from firing. Inside your before_beacon event handler, simply remove all parameters.

BOOMR.subscribe('before_beacon', function(o) {
	var p_names = [], k;

	if( "t_done" in o ) {
		return;
	}

	// t_done is not set, so don't beacon         
	for(k in o) {
		if(o.hasOwnProperty(k)) {
			p_names.push(k);
		}
	}

	// removeVar accepts either a list or an array
	BOOMR.removeVar(p_names);
});

The latest code and docs is available on github.com/lognormal/boomerang