An example usage of Google Experiments on client side only

call-sample.html

<!-- Call immediately an experiment method to prevent  a FOOC (Flash of original content) -->
<button class="btn btn-link" type="button" id="button">Click me</button>
<script>typeof __abt !== "undefined" && __abt.some && __abt.some();</script>

<div classs="another-html-content"></div>

ga-experiment.js

// Global var to handle the variations
window.__abt = window.__abt || {};

// Important! Use the same domain name as in GA
cxApi.setDomainName('none');

// Experiment's variations
var someExp = [
  function () {
    // Original, no change
  },
  function () {
    // Do something 1
  },
  function () {
    // Do something 2
  }
],
// Configured Google experiment ID for an account button
experimentId = 'XXXXXXXXXXXXXXXXXXXXXX';

// The variation chosen for the visitor
var chosenVariation = cxApi.getChosenVariation(experimentId);

// First visit, choose randomly some variation
if (chosenVariation === cxApi.NO_CHOSEN_VARIATION) {
  chosenVariation = Math.floor(Math.random() * someExp.length);
  cxApi.setChosenVariation(chosenVariation, experimentId);
}

// Expose variation method to the global scope
if (chosenVariation === cxApi.NOT_PARTICIPATING) {
  // Do nothing when user is not a participant
  __abt.some = someExp[cxApi.ORIGINAL_VARIATION];
} else {
  // Set the apropriate method
  __abt.some = someExp[chosenVariation];
}