Let's talk about the reasons and solutions for webview not calling javascript

In Android development, Webview is a commonly used control for embedding web pages or other HTML components in applications. However, sometimes when using Webview, you may encounter the problem that Webview does not call JavaScript. This article will mainly introduce the causes and solutions to this problem.

1. Problem description

In some cases, we will find that Webview does not successfully call JavaScript, even if we have confirmed that JavaScript is correct in the code. Our webview doesn't get any exceptions or errors, and may even still load other web pages successfully, it's just that the JavaScript isn't being called. At this time, we need to think about the root of the problem.

2. Cause of the problem

Generally speaking, the reasons why Webview does not call JavaScript may be as follows:

1. Permission problem

If you If the application does not have sufficient permissions to access JavaScript at runtime, the Webview may not call JavaScript. In this case, you can add the necessary permission requests in your code so that your app gets the required permissions on startup.

2. Code problem

If there is a problem with your JavaScript code, Webview may not call JavaScript. Wrong character formatting, spelling mistakes, and other grammatical errors can cause code to not work. It is recommended that you use Webview's console to view JavaScript errors and make adjustments accordingly when debugging your code.

3. Web page URL problem

If your URL contains wrong characters or domain names, Webview may not be able to load the web page, resulting in the inability to call JavaScript. At this point, you need to check whether your URL contains spaces, invalid characters, or incorrect domain names, and change it accordingly.

4. Security issues

In some cases, to ensure security, Webview may not allow us to call JavaScript. A common situation is that Webview blocks JavaScript calls when the application loads an untrusted web page. In this case, you can solve the problem by moving the page to the server or providing the necessary security certification.

3. Solution

For the problem that Webview does not call JavaScript, we can take the following methods:

1. Check permissions

First, You need to check if your application has the required permissions to run. If you don't have the appropriate permissions, you'll need to add a statement in your code requesting permissions so that you get the required permissions when your application starts.

2. Check the code

If there is a problem with your JavaScript, you need to use the Webview's console to view the code errors. Check formatting, spelling and grammar in JavaScript and adjust accordingly.

3. Check the web page URL

If your URL contains wrong characters or domain names, you need to find and change the corresponding errors in the URL. Make sure your URL contains the correct domain name and parameters.

4. Relax security settings

If your application needs to obtain information from an untrusted website, you may need to relax the security settings of Webview to allow JavaScript calls. To do this, you need to write the appropriate code to toggle the Webview's security settings when loading the web page. Note that this method may pose some security risks, so use it with caution.

In short, if you encounter the problem of Webview not calling JavaScript, you need to first determine the root cause of the problem. Once you've identified the problem, you can take steps to resolve it and ensure your application can call JavaScript smoothly. In this way, you can easily create more advanced and dynamic Webview applications.

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