Wordpress 手動增加 Google Analytics 追蹤程式碼

add_action('wp_head', 'google_analytics');

function google_analytics() {  
    echo "<script>  
 (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){  
 (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),  
 m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)  
 })(window,document,'script','//www.google-analytics.com/analytics.js','ga');

ga('create', '追蹤碼', '網址');  
ga('send', 'pageview');

</script>";   
}