Var Issue

This repo demonstrates an issue that I'm experiencing and have trouble explaining. This issue is this.

I have a React Native app that uses a WebView component. The webview has some static HTML (i.e. does not load anything external). I then use the injectedJavaScript property to load Javascript into it. This piece of JavaScript declares two variables in the "global" scope (i.e. window in this case): xx and yy. The difference is that xx is declared with the var keyword, whereas yy is not. Furthermore, it declares a function f that appends a string to the WebView's body.

Next, after a timeout of a second, another piece of JavaScript is executed on the WebView using injectJavaScript. This demonstrates that on iOS both variables and the function are available and can be used. On Android, however, only yy is available; both xx and the function f are unavailable.

iOS Output

On iOS you can see that the function f was called and that the two variables are available:

Android Output

On Android both xx and f are not defined.

Note / Workaround

Please note that declaring the variables and function using injectJavaScript instead of injectedJavaScript causes everything to work as expected, both on Android and on iOS.

Versions

• Android 9 / iOS 11
• react-native-webview: 5.8.1
• yarn react-native info:

  React Native Environment Info:
    System:
      OS: macOS 10.14.4
      CPU: (12) x64 Intel(R) Core(TM)   i7-8850H CPU @ 2.60GHz
      Memory: 18.87 MB / 16.00 GB
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 11.14.0 - /var/folders/0d/  5_t6qk7s06qf94jnypzwh6yh0000gp/T/  yarn--1557086445011-0.  06815149805556375/node
      Yarn: 1.15.2 - /var/folders/0d/  5_t6qk7s06qf94jnypzwh6yh0000gp/T/  yarn--1557086445011-0.  06815149805556375/yarn
      npm: 6.9.0 - ~/.homebrew/bin/npm
    SDKs:
      iOS SDK:
        Platforms: iOS 12.2, macOS   10.14, tvOS 12.2, watchOS 5.2
    IDEs:
      Xcode: 10.2.1/10E1001 - /usr/bin/  xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3
      react-native: 0.59.5 => 0.59.5