Thursday, May 7, 2020

Identifying if a Teams personal app runs from Teams Web or Teams Desktop Client

I’ve recently built a Teams personal app that required a different authentication mechanism when running from Teams desktop client. It took me a while to figure out how to distinguish between Teams desktop client and Teams web. As far as I’ve researched, there is no supported way yet to clearly identify where a personal app is running. Hence, I decided to write this blog post which shows how to identify if a Teams personal app runs from Teams web or Teams desktop client.



In my case, I tried to embed a SharePoint page as a Teams personal app. This page had a SharePoint Framework web part which did not run from Teams desktop client without a special authentication algorithm. For different reasons, it was not feasible to utilize this new authentication logic in both scenarios: Teams web and Teams desktop client. Well, it was clear. I had to find a way around this!

After intensive platform comparison, I observed two special characteristics. The document interface (loaded web page representation in the browser) and the navigator interface (identity of the browser):

1. document.referrer

When a Teams personal app runs from Teams web, the referrer can contain a value like: https://teams.microsoft.com/_. When the same personal app runs from Teams desktop client the referrer will then be: https://teams.microsoft.com/iframe-container.html. However, the referrer might change depending on operations executed from the embedded page. Hence, the referrer property is not reliable and didn’t help me in that case. 

2. navigator. userAgent

When a Teams personal app runs from Teams desktop client the userAgent always contain the Teams agent. This is a value which consists of Teams/{version} such as Teams/1.3.00.12058. In case of Teams web, the userAgent property doesn't contain the Teams agent. That made the tweak in my case! 


Summary:

Checking if the value "Teams/" existed in the userAgent property, helped me to identify when my personal app was running from Teams web or Teams desktop client. I am constantly looking for an out of the box solution and hope that Microsoft will provide it soon!

I hope this blog post helps you not spending hours trying to understand the uniqueness of those two platforms.

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