Does JavaScript naming specification raise compatibility issues in Android WebView?

Analysis and solution of compatibility issues between Android WebView and JavaScript naming specifications

The naming specification of JavaScript code is crucial. Best practices recommend using letters, numbers, underscores and dollar signs, and the first character cannot be a number. However, recently when integrating the pdfjs-dist library, we found a compatibility issue: code running normally in Chrome browsers, but syntax errors (unexpected tokens) are thrown in Android WebView. The root cause is that the pdf.js file uses function names starting with the pound sign (#), which is not supported in some Android WebView versions.

The pound sign (#) is used in some programming languages ​​to represent private members, but this is not the JavaScript standard. Older versions of Android WebView cannot resolve this non-standard naming method, resulting in syntax errors.

It is not a best practice to directly modify pdfjs-dist package under node_modules , because it is easily overwritten when updating dependent packages. A better approach is to use the configuration of the build tool to solve compatibility issues.

We solved this problem by following the steps:

1. .browserslistrc file configuration: This file specifies the target browser and version to ensure code compatibility. Since the version number rules of Android WebView and Chrome Android are different, you need to specify them separately:

 <code>android >= 4 chromeandroid >= 83 last 2 versions</code>

2. transpileDependencies in vue.config.js (or similar configuration file) : Since Babel does not handle dependency package code by default, it is necessary to explicitly specify the dependency package that needs to be translated in the configuration file, for example:

 module.exports = {
  transpileDependencies: ['pdfjs-dist'],
  // ... other configurations
}

3. include in babel.config.js (or similar configuration file) : explicitly specify the code directory that Babel needs to process, and ensure that both src directory and node_modules/pdfjs-dist are included:

 module.exports = {
  Presets: [],
  plugins: [],
  include: [path.resolve('src'), path.resolve('node_modules/pdfjs-dist')],
};

Through the above configuration, we have successfully solved the compatibility issue in Android WebView. However, even if the naming specification problem is solved, we still encounter the problem of PDF display misalignment, which reminds us that when dealing with cross-platform compatibility, we need continuous debugging and optimization to ensure the stability and consistency of the application in different environments.

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