How can you choose variations for several content experiments?

Question

I\'m using the Javascript API for Google Analytics Content Experiments and it seems like you have two choices:

1. Run one experiment at a time and have Google ass

Answer 1

This solution works very well for me. The benefits are:

• no node.js required
• no changes to site needed - site remains fully cacheable
• Google Multi-Armed-Bandit approach used, no patch
• easily maintainable

Javascript Module providing all functionality for executing multiple Google Experiments:

var runExperiment = (function(jQ) {

    var apiUrl = '/ga-experiments-api.php?preview=true&experimentId=',
        experimentId,
        variations;

    var chooseAndApplyNewVariation = function() {
        if (typeof jQ !== 'undefined') {
          jQ.ajax({
              type: 'get',
              url: apiUrl + experimentId,
              success: function(data, status){
                  var choosenVariation = data.choosenVariation;

                  if (typeof choosenVariation !== 'undefined' && choosenVariation >= 0) {
                      cxApi.setChosenVariation(choosenVariation, experimentId);
                      applyVariation(choosenVariation);
                  }
              }
          });
        }  
    };

    var applyVariation = function(chosenVariation) {
        var variationFunction = (typeof variations[chosenVariation] === 'function') ? variations[chosenVariation] : false;

        if (variationFunction) {

            variationFunction.apply();
            sentGaEvent();
            console.log(experimentId, chosenVariation);
        }
    };

    var sentGaEvent = function() {
        if (typeof ga !== 'undefined') {
            ga('send', 'event', 'experiment', 'view');
        }
    };

    return function(experiment) {
        experimentId = experiment.id;
        variations = experiment.variations;

        if (typeof cxApi !== 'undefined') {

            var chosenVariation = cxApi.getChosenVariation(experimentId);

            if (chosenVariation >= 0) {

                applyVariation(chosenVariation);

            } else {

                chooseAndApplyNewVariation();
            }
        }
    };
})(jQuery);

Javascript Snippet for running single experiment - can be integrated multiple times on page:

(function(jQ) {
    var experiment = {
        'id': 'RHwa-te2T_WnsuZ_L_VQBw',
        'variations': [
            function() {},
            function() {
                jQ('#nav #menu-item-2000927 a').text('Shop + Abo');
            }]
    };

    runExperiment(experiment);
}(jQuery));

PHP (API) for generating new variations through Google's API, I used this class:

https://github.com/thomasbachem/php-gacx

 $experimentId,
);

try {
    $experiment = new GoogleAnalytics\Experiment($experimentId);

    $variation = $experiment->chooseNewVariation();

    if (is_integer($variation)) {

        $returnData['success'] = true;
        $returnData['choosenVariation'] = $variation;
    }

} catch (Exception $exception) {

    $returnData['success'] = false;
    $returnData['error'] = $exception;
}

header('Content-Type: application/json');

echo json_encode($returnData);