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  • Overcoming Content Security Policy (CSP) restrictions for GA4 on Chrome Extension

    Posted by Harper on 21 April 2023 at 7:28 pm

    Hey there!

    Looks like I’m in a bit of a pickle! I’ve been having a go at developing a Chrome Extension and I want to use GA4 for analytics. So, for my manifest.json (v2), I’ve written something like this:

    `javascript
    “background”: {
    “scripts”: [“src/bg/background.js”, “src/bg/ga4.js”],
    “persistent”: true
    },
    “content_security_policy”: “script-src ‘self’ https://www.googletagmanager.com; object-src ‘self'”
    `

    I’ve then tried to add the following in ga4.js:

    `javascript
    var script = document.createElement(‘script’); script.type = ‘text/javascript’; script.async = true;
    script.src = ‘https://www.googletagmanager.com/gtag/js?id=G-*******’;
    var s = document.getElementsByTagName(‘script’)[0]; s.parentNode.insertBefore(script, s);

    window.dataLayer = window.dataLayer || [];
    function gtag(){dataLayer.push(arguments);}
    gtag(‘js’, new Date());

    gtag(‘config’, ‘G-******’);
    `

    First hitch! I’m faced with an error saying that the script ‘https://www.googletagmanager.com/gtag/js?id=G-******’ is refusing to load because it apparently violates the Content Security Policy directive.

    I thought of fixing it by using a background HTML page and adding the script snippet from GA4 to the <head> tag, but no such luck! If I do that, my extension breaks.

    So what’s the secret to struggling through this CSP hurdle? Has anyone run into this and found a way around it?

    Charlotte replied 11 months, 2 weeks ago 3 Members · 2 Replies
  • 2 Replies
  • Noah

    Member
    13 May 2023 at 12:44 pm

    The issue you are encountering is rooted in how Chrome Extensions handle the Content Security Policy. Google currently limits the resources that can be loaded by a Chrome extension to improve security. This poses a challenge though as direct access to the analytics script is blocked. This is done to protect extension users from inadvertently executing harmful scripts. One possible workaround to bypass the limitation does not involve directly calling the script. You can make use of the Measurement Protocol by Google Analytics to send HTTP requests. Here, you would instantiate an XMLHttpRequest (or fetch) in your JavaScript file and use it to send pageview or event data to Google Analytics. While it’s a more roundabout way as it requires forming and sending HTTP request instead of simply embedding the script tag, it gets around the CSP restrictions in the manifest.json file.

  • Charlotte

    Member
    30 June 2023 at 7:30 am

    Unfortunately, the issue you’re facing originates from the fact that the Chrome Extensions Content Security Policy (CSP) does not allow inline scripts to be executed and only allows scripts loaded from HTTPS sources.
    However, one does not have the authority to alter this policy.

    Therefore, you would need to pull in the GA4 script and host it locally within your extension. Then, you’d have to include it from your manifest.json file and access it as ‘self’.

    Moreover, Google Analytics (GA) also utilizes inline scripts, which is another no-go as per the security policies of Chrome Extensions. Thus, you will need to modify the GA script to allow the creation of script tags dynamically or find another way to execute your GA tracking.

    It could be that little bit easier if you made use of the chrome.tabs.executeScript API to inject your GA code into the context of web pages loaded in your user’s browser. Alternatively, you could also look at using an analytics service that offers a library specifically designed for browser extensions, such as the Beacon API.

    Remember, when modifying the CSP, be utterly sure that it does not expose your extension to the risk of XSS attacks.

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