wp-ga-opt-out.md

WordPress: Goggle Analytics Opt-Out

I have a modest blog. One day I might care about Google Anaylitcs. For now, my basic needs are:

• Add a GA global tag to the site head.
• Present users with a way to opt-out of GA for my site.
• Display this option on the Privacy Policy page - Settings > Privacy.

For this, I'm using:

• wp_head to add the Google scripts - one for tracking + one for opt-out.
• get_option to find the Privacy Policy page and conditionally add the opt-out script.
• add_shortcode for placing the opt-out link anyewhere needed.

To test if things are working:

• Check the GA global tag appears on all site pages.
• Check the GA opt-out script appears on just the Privacy Policy page.
• Check that when user clicks the opt-out, an alert is displayed.
• Use your browser's dev tools to check for the ga-disable cookie.

In Chrome: Dev Tools > Application tab > Left nav > Storage: Cookies > Site Name

// Add GA Global Tag to site `head`
// Replace 2 instances of `UA-XXXXXXXXX-X` with property (account) ID.

function knotty_ga_global_tag() { 
	?>
	<!-- Global site tag (gtag.js) - Google Analytics -->
	<script async src="https://www.googletagmanager.com/gtag/js?id=UA-XXXXXXXXX-X"></script>
	<script>
		window.dataLayer = window.dataLayer || [];
		function gtag(){dataLayer.push(arguments);}
		gtag('js', new Date());
		gtag('config', 'UA-XXXXXXXXX-X');
	</script>
	<?php 
}
add_action( 'wp_head', 'knotty_ga_global_tag', 1 );

// Opt-Out of GA for this site
// Since we are only presenting this option on the Privacy Page,
// we only need the GA opt-out script in this page's `head`
// https://wordpress.stackexchange.com/a/314372

$privacy_policy_page = get_option( 'wp_page_for_privacy_policy' );

if( $privacy_policy_page ) : 
    function knotty_ga_opt_out(){     
        ?>
        <!-- Disable Google Analytics for this site -->
        <script>
            // Replace `UA-XXXXXXXXX-X` with property ID
            var gaProperty = 'UA-XXXXXXXXX-1';
            var disableStr = 'ga-disable-' + gaProperty;
            if (document.cookie.indexOf(disableStr + '=true') > -1) {
                window[disableStr] = true;
                
            }
            function gaOptout() {
                document.cookie = disableStr + '=true; expires=Thu, 31 Dec 2099 23:59:59 UTC; path=/';
                window[disableStr] = true;
                alert('Google Analytics has been disabled for this site.');
            }
        </script>
        <?php
    }
    add_action( 'wp_head', 'knotty_ga_opt_out', 1 );
endif;	

// Create `[ga_opt_out]' shortcode
function knotty_ga_opt_out_button() {
    $return = '<a href="javascript:gaOptout()">Opt out of Google Analytics for this site</a>';
    return $return;
}

// Register and initialize shortcode
function knotty_register_ga_opt_out() {
   add_shortcode( 'ga_opt_out', 'knotty_ga_opt_out_button' ); 
}
add_action( 'init', 'knotty_register_ga_opt_out');