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One of the recurring problems in migrating to Google Tag Manager is how to make the transition as smooth as possible. Usually it requires that we agree with the developers on a time when the old code is removed, and at that moment we need to make sure the GTM tags point to the right UA code. This is, of course, only one use case for migrations, as some people do the entire migration in a staging environment, and some just don\u2019t care if they lose a little bit of data along the way.<\/p>\n
However, the most seamless way to do the transition is to automate it. Make GTM somehow check for the existence of on-page GA, and if it finds it, the tags will not fire. As soon as the on-page GA is no longer found, GTM can go rampart.<\/p>\n
This is a recurring discussion in our Google+ GTM Community<\/a>, but this time it began in Twitter.<\/p>\n In this post, I wanted to take a shot at what my good friend Peter is looking for, with what I think is the best way to do this.<\/p>\n Now, there are a number of ways you could go about checking for on-page GA, including:<\/p>\n Check for existence of GA cookies<\/p>\n Serialize page template, and regex match for script loaders or calls to the tracking objects<\/p>\n Ask developers to add Check for existence of But I want to show you what I think is the best way to do it. Feel free to disagree, and I find myself disagreeing with me as well, especially on a complex site! In my opinion, the following solution does the check as early as possible, and it\u2019s as reliable as it can be, even though there are some caveats.<\/p>\n \n \n Subscribe to the Simmer newsletter<\/a> to get the latest news and content from Simo Ahava into your email inbox!\n <\/p>\n <\/span><\/p>\n\n
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dataLayer.push()<\/code> that tells the status of on-page GA<\/p>\n\n
ga<\/code> or _gaq<\/code> objects<\/p>\n\n
ga<\/code> object, so you\u2019d need to identify it first.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n X<\/span><\/p>\n
\n The Simmer Newsletter<\/strong>\n <\/p>\nSolution: look for the