Google Tag Manager (GTM)

Inbound Integration (Events flow from GTM dataLayer to Statsig)

This integration will allow customers using Statsig on the web to leverage their existing Google Tag manager configuration to track events to Statsig. This saves customers from having to retag their web properties with calls specific to Statsig's SDK. This integration uses a global listener to consume all GTM triggers and dispatch a corresponding event back to Statsig.

(statsig log stream showing GTM events flowing in)

Setup

Step 1: Broadcast Statsig client readiness to GTM

The tracking code within GTM will need to know when the Statsig client is ready to use for tracking. To do so, you'll need to broadcast a window-level event and pass the statsig instance for the GTM tag code to use. In your initialize call, implement the initCompletionCallback callback as follows:

Using @statsig/js-client

window.statsig = new Statsig.StatsigClient('<CLIENT-SDK-KEY>', {/* USER */}, {/* OPTIONS */});
statsig.on('values_updated', function(evt) { // bind before init is called
  if(evt.status && evt.status === 'Ready') {
    window.dispatchEvent(new CustomEvent("statsig:ready", {
      detail: { statsig: statsig }
    }));        
  }
});
await statsig.initializeAsync();

Using statsig-js

await statsig.initialize('<CLIENT-SDK-KEY>', '<USER-OBJECT>', {
  initCompletionCallback: function (duration, success, message) {
    window.dispatchEvent(new CustomEvent("statsig:ready", {
      detail: { statsig: statsig }
    }));
  }
}); 

Step 2: Create new tag

Step 3: Choose tag type

Choose "Custom HTML" for tag type, and paste this GTM code (including script tag)

Step 4: Adjust fire options

Under Advanced Settings under "Tag Firing options", select "Once per page"

Step 5: Set Tag Trigger

Below the "Tag Configuration" section, set the Trigger to "Initialization - All Pages" Option.

Step 6: Save tag and test

After saving the tag, and publishing your updated GTM tag, tracking will be done automatically without any additional configuration. To debug the integration, you can set a local storage entry debug_ss_gtm with any value on your webpage. Now, you'll console log statements for each tracking call being dispatched to Statsig. You can also inspect your browser's network traffic to see events being tracked.

GTM Code

info

The code below assumes that the statsig client lives at window.statsig

<script type="text/javascript">
/* dataLayer helper */
(function(){
var f=/\[object (Boolean|Number|String|Function|Array|Date|RegExp|Arguments)\]/;function g(a){return null==a?String(a):(a=f.exec(Object.prototype.toString.call(Object(a))))?a[1].toLowerCase():"object"}function m(a,b){return Object.prototype.hasOwnProperty.call(Object(a),b)}function n(a){if(!a||"object"!=g(a)||a.nodeType||a==a.window)return!1;try{if(a.constructor&&!m(a,"constructor")&&!m(a.constructor.prototype,"isPrototypeOf"))return!1}catch(c){return!1}for(var b in a);return void 0===b||m(a,b)};function p(a,b){var c={},d=c;a=a.split(".");for(var e=0;e<a.length-1;e++)d=d[a[e]]={};d[a[a.length-1]]=b;return c}function q(a,b){var c=!a._clear,d;for(d in a)if(m(a,d)){var e=a[d];"array"===g(e)&&c?("array"===g(b[d])||(b[d]=[]),q(e,b[d])):n(e)&&c?(n(b[d])||(b[d]={}),q(e,b[d])):b[d]=e}delete b._clear};
function r(a,b,c){b=void 0===b?{}:b;"function"===typeof b?b={listener:b,listenToPast:void 0===c?!1:c,processNow:!0,commandProcessors:{}}:b={listener:b.listener||function(){},listenToPast:b.listenToPast||!1,processNow:void 0===b.processNow?!0:b.processNow,commandProcessors:b.commandProcessors||{}};this.a=a;this.l=b.listener;this.j=b.listenToPast;this.g=this.i=!1;this.c={};this.f=[];this.b=b.commandProcessors;this.h=u(this);var d=this.a.push,e=this;this.a.push=function(){var k=[].slice.call(arguments,
0),l=d.apply(e.a,k);v(e,k);return l};b.processNow&&this.process()}r.prototype.process=function(){this.registerProcessor("set",function(){var c={};1===arguments.length&&"object"===g(arguments[0])?c=arguments[0]:2===arguments.length&&"string"===g(arguments[0])&&(c=p(arguments[0],arguments[1]));return c});this.i=!0;for(var a=this.a.length,b=0;b<a;b++)v(this,[this.a[b]],!this.j)};r.prototype.get=function(a){var b=this.c;a=a.split(".");for(var c=0;c<a.length;c++){if(void 0===b[a[c]])return;b=b[a[c]]}return b};
r.prototype.flatten=function(){this.a.splice(0,this.a.length);this.a[0]={};q(this.c,this.a[0])};r.prototype.registerProcessor=function(a,b){a in this.b||(this.b[a]=[]);this.b[a].push(b)};
function v(a,b,c){c=void 0===c?!1:c;if(a.i&&(a.f.push.apply(a.f,b),!a.g))for(;0<a.f.length;){b=a.f.shift();if("array"===g(b))a:{var d=a.c;g(b[0]);for(var e=b[0].split("."),k=e.pop(),l=b.slice(1),h=0;h<e.length;h++){if(void 0===d[e[h]])break a;d=d[e[h]]}try{d[k].apply(d,l)}catch(w){}}else if("arguments"===g(b)){e=a;k=[];l=b[0];if(e.b[l])for(d=e.b[l].length,h=0;h<d;h++)k.push(e.b[l][h].apply(e.h,[].slice.call(b,1)));a.f.push.apply(a.f,k)}else if("function"==typeof b)try{b.call(a.h)}catch(w){}else if(n(b))for(var t in b)q(p(t,
b[t]),a.c);else continue;c||(a.g=!0,a.l(a.c,b),a.g=!1)}}r.prototype.registerProcessor=r.prototype.registerProcessor;r.prototype.flatten=r.prototype.flatten;r.prototype.get=r.prototype.get;r.prototype.process=r.prototype.process;window.DataLayerHelper=r;function u(a){return{set:function(b,c){q(p(b,c),a.c)},get:function(b){return a.get(b)}}};})(); 

window.StatsigLogger = (function () {

  var statsigInstance;
  var log = function () {
    if (typeof localStorage !== 'undefined' && typeof console !== 'undefined' && localStorage.getItem('debug_ss_gtm')) {
      console.log.apply(console, arguments);
    }
  };

  var handleGTMMessage = function (model, message) {    
    if (typeof message === 'object' && typeof message.event === 'string') {
      var metadata = {};
      for (var prop in message) {
          if(!(message[prop] instanceof HTMLElement) && typeof(message[prop]) !== 'object') {
            metadata[prop] = message[prop];
          }
      }
      log('++ handleGTMMessage', message.event, message.conversionValue || null, metadata);
      statsigInstance.logEvent(message.event, message.conversionValue || null, metadata);
    }
    else {
      log('++ handleGTMMessage / skip');
    }
  }
  
  var init = function(condition) {
    log('+++ Statsig:ready ->', condition);
    // this may have past messages that haven't yet been handled
    var globalGTMListener = new DataLayerHelper(dataLayer, {
      listener: handleGTMMessage,
      listenToPast: true,
    });        
  }

  var clientReady = false;
  try {
    // The code below assumes that the statsig client lives at `window.statsig`
    clientReady = (statsig && statsig.getClientX && statsig.getClientX().ready) || statsig.loadingStatus === 'Ready';
  } catch(err) { }
  
  if(clientReady) {
    // if client is already initialized, proceed
    statsigInstance = statsig;
    init('pre-GTM');
  }
  else {
    // otherwise wait for statsig
    window.addEventListener('statsig:ready', function(evt) {
      statsigInstance = evt.detail.statsig;
      init('post-GTM');
    });  
  }

})();  
</script>

Outbound Integration (GTM Data is enriched with Statsig test assignments)

This pattern will allow you to enrich your GTM dataLayer with experiment assignment information.

Prior to your Statsig initialize call, you should bind an EventEmitter listener that captures the assigned experiment name and test group, and push it into the dataLayer as follows. Note that the argument passed to the callback contains rich context about the assignment. Please modify the GTM dataLayer properties to your liking.

// use event emitter to listen for experiment assignments
statsigClient.on("experiment_evaluation", function(evt) {
  window.dataLayer.push({
    'event': 'experiment_viewed',
    'experiment_name': evt.experiment.name, 
    'variant_name': evt.experiment.groupName
  })
});

await statsigClient.initializeAsync();