@Diskdance Great question, and as it happens, I think this is trivially simple:

if (pcsClient) {
  // running in WebView.
  ...
}

The pcsClient object is a global variable that is exposed as a "bridge" between the WebView and the native app for exchanging messages. Therefore, if this object exists, it means you're running inside a WebView in the app. (More formally, you can check for typeof pcsClient !== 'undefined')

This is technically true for both the Android and iOS WebViews. However, the iOS app does not make its WebView aware of your login state (it does not share cookies with the WebView), so when the iOS app loads a regular HTML version of a page, it will not load any user javascript.
So to summarize, for Android it's trivial, and for iOS it's moot.

In T357497#9542030, @Dbrant wrote:

@Diskdance Great question, and as it happens, I think this is trivially simple:

if (pcsClient) {
  // running in WebView.
  ...
}

The pcsClient object is a global variable that is exposed as a "bridge" between the WebView and the native app for exchanging messages. Therefore, if this object exists, it means you're running inside a WebView in the app. (More formally, you can check for typeof pcsClient !== 'undefined')

This is technically true for both the Android and iOS WebViews. However, the iOS app does not make its WebView aware of your login state (it does not share cookies with the WebView), so when the iOS app loads a regular HTML version of a page, it will not load any user javascript.
So to summarize, for Android it's trivial, and for iOS it's moot.

Glad to know this! My requirement is to make it for default gadgets, so this satisfies my needs.

Is there a way to test this out on Beta Cluster? Looks like the app is bound to the production endpoint.

In T357497#9542274, @Diskdance wrote:

Is there a way to test this out on Beta Cluster? Looks like the app is bound to the production endpoint.

It's a bit clunky, but possible:

• Enable Developer Mode in the app (go to the app's settings, then "About the Wikipedia App", then tap seven times on the globe icon)
• Go back to Settings, the go into Developer Settings (icon at top-right corner of the Settings screen)
• One of the developer settings is called mediaWikiBaseUri, which is the "base" URL for all mediawiki requests, which defaults to the production environment. If you want to point it to the Beta cluster, you can change this setting to https://wikipedia.beta.wmflabs.org.
• Close and reopen the app for the change to take effect.