Dynamically Adding Google Analytics and Data Layer On Accept Cookies

user_3083472 0
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I am trying to add Google Analytics to my site dynamically only after the use clicks "I Accept Cookies".

The script that I have so far is

<script>
  function addScript() {
    var addGoogleAnalytics = document.createElement("script");
    addGoogleAnalytics.setAttribute("src","https://www.googletagmanager.com/gtag/js?id=G-MYIDHERE");
    addGoogleAnalytics.async = "true";
    document.head.appendChild(addGoogleAnalytics);

    var addDataLayer = document.createElement("script");
    var dataLayerData = document.createTextNode("window.dataLayer = window.dataLayer || []; \n function gtag(){dataLayer.push(arguments);} \n gtag('js', new Date()); \n gtag('config', 'G-MYIDHERE');");
    addDataLayer.appendChild(dataLayerData);
    document.head.appendChild(addDataLayer);
  }
</script>

This is triggered using a simple

<a href="#" onclick="addScript();">Click Here</a>

This seems to work fine, but my questions are:

  1. Is there a better way to do this? I am no expert at javascript, so I am a little surprised it works and want to make sure there are no major code/security risks before deploying.

  2. More importantly.. How do I store the "I accept" in a cookie or localStorage so that they do not have to click I accept each time, and if that is set it loads the script automatically without the onclick function?

google-analytics javascript
1 Answers

So the problem with the above was that the code showed the cookie notice on every page.

<script>
var cookies = localStorage.getItem("cookiesAccepted");
// this checks if cookies local storage was accepted before
if(cookies == 'Yes') {

//if they were it creates the analytics tag

    var addGoogleAnalytics = document.createElement("script");
    addGoogleAnalytics.setAttribute("src","https://www.googletagmanager.com/gtag/js?id=G-MYIDHERE");
    addGoogleAnalytics.async = "true";
    document.head.appendChild(addGoogleAnalytics);

    var addDataLayer = document.createElement("script");
    var dataLayerData = document.createTextNode("window.dataLayer = window.dataLayer || []; \n function gtag(){dataLayer.push(arguments);} \n gtag('js', new Date()); \n gtag('config', 'G-MYIDHERE');");
    addDataLayer.appendChild(dataLayerData);
    document.head.appendChild(addDataLayer);
}

//if cookies were not set to yes, it waits for the cookie banner click function.

function addScript() {
    localStorage.setItem('cookieAccepted', 'Yes');
    var addGoogleAnalytics = document.createElement("script");
    addGoogleAnalytics.setAttribute("src","https://www.googletagmanager.com/gtag/js?id=G-MYIDHERE");
    addGoogleAnalytics.async = "true";
    document.head.appendChild(addGoogleAnalytics);

    var addDataLayer = document.createElement("script");
    var dataLayerData = document.createTextNode("window.dataLayer = window.dataLayer || []; \n function gtag(){dataLayer.push(arguments);} \n gtag('js', new Date()); \n gtag('config', 'G-MYIDHERE');");
    addDataLayer.appendChild(dataLayerData);
    document.head.appendChild(addDataLayer);
  }
</script>

This code above seems to work. If the user already accepted cookies it adds the Google Analytics tag without prompting the user. If they have not accepted the prompt is used to trigger the addscript function on accept.

user_30834720
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