ASP.NET/C# Add Code to existing Website

We currently add google tag manager code into the tag of the website. All websites share the same ‘site.master’ and many other files so the code is modified to take an ‘ID’ variable from the web.config file. The GTM code is only placed into the website once the cookie consent has been accepted. I can share code excerpts on first contact.

Current code looks like this, as an example of the type of project:

private void GoogleTagManagerTag(string id)
{
googleTagManager.Text = @"

(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','" + id + @"');";
}