Скачать или смотреть Resolving Javascript Square Bracket Notation Issues in Android WebView

Learn how to fix the Javascript notation error in Android WebView by understanding common pitfalls and solutions.
---
This video is based on the question https://stackoverflow.com/q/60340425/ asked by the user 'Yunus Emre' ( https://stackoverflow.com/u/10939108/ ) and on the answer https://stackoverflow.com/a/63360901/ provided by the user 'Yunus Emre' ( https://stackoverflow.com/u/10939108/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Javascript square bracket notation couldn't be evaluated properly while using an android webview. Any advice to fix it?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving Javascript Square Bracket Notation Issues in Android WebView

When working with Android WebView, developers sometimes encounter issues with dynamic function calls over the Javascript Interface, especially when using square bracket notation. Recently, one developer faced a frustrating error:

[[See Video to Reveal this Text or Code Snippet]]

This error indicates that the JavaScript interpreter cannot locate the method referenced by key. Thankfully, there are solutions to this problem that can get your code back on track. In this post, we will explore the potential reasons behind the issue and how to resolve them effectively.

Understanding the Issue

The error occurs when Javascript tries to call a method dynamically using square bracket notation. The key points to note here are:

The code works fine in a standard web browser.

The error only appears within the Android WebView context.

Possible Causes of the Error

Here are two main reasons why this issue may arise in your code:

Missing @ JavascriptInterface Annotation: Without this annotation, the methods defined in your Android code may not be accessible from JavaScript, causing the call to fail.

Method Missing or Parameter Mismatch: If the method you are trying to call doesn’t exist in the AndroidBridge class or the parameters do not match what is expected in your code, this can lead to the error you are experiencing.

Solution Steps

Now that we've identified possible causes, let's dive into the solution. Below are the steps to ensure your dynamic method calls are correctly set up in the Android WebView.

Step 1: Add the @ JavascriptInterface Annotation

Ensure that you have included the @ JavascriptInterface annotation on all methods that you want to expose to JavaScript. This annotation is crucial for enabling interaction between your Android code and JavaScript.

Example

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Add the JavaScript Interface to the WebView

In your activity or fragment, ensure that you are adding the JavaScript interface correctly like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Call Methods from JavaScript

You can now call methods accurately from your JavaScript code using both dot notation and square bracket notation.

Example Calls

[[See Video to Reveal this Text or Code Snippet]]

Both methods should work seamlessly, allowing you to display toast messages or perform other actions defined in your interface.

Conclusion

Dynamic function calls using square bracket notation in an Android WebView can be tricky, especially when dealing with Javascript Interfaces. By ensuring that you properly annotate your methods and confirm that they exist with the correct parameters, you can overcome the common pitfalls and successfully execute your JavaScript commands.

With these steps, you should be able to troubleshoot and fix the TypeError error effectively and keep your application running smoothly. If you continue to experience issues, double-check your method definitions and ensure that all necessary annotations are correctly applied.

Happy coding!