Example: Code Generation with Rspack

This example demonstrates how to use Rspack for generating code at build time and executing it at runtime.

What’s Happening in the Code

Overview:

In this example, we use Rspack to generate a JavaScript file at build time that contains a dynamic function. This function is then executed at runtime.

Code Breakdown:

1. CodeGenPlugin.js:

   • This is a custom Rspack plugin responsible for generating JavaScript code at build time.
   • The plugin creates a generated.js file inside the dist folder.
   • The generated code exports a simple function dynamicGreeting which logs a greeting message.

2. Rspack Configuration:

   • The plugin is added to the rspack.config.js file under the plugins section.
   • The configuration ensures that the plugin runs at the appropriate phase during the Rspack build process.

3. Generated Code (generated.js):

   • This file contains the generated dynamicGreeting function, which will be executed at runtime.
   • The code is simple: it logs a greeting message with a dynamic input.

4. Runtime Execution (index.js):

   • The main code in index.js imports the dynamicGreeting function from generated.js and executes it.
   • The generated.js file is dynamically injected by the plugin at build time.
   • The dynamicGreeting function is called during runtime to display a greeting message.

How It Works:

• Rspack compiles the project using the custom plugin.
• At build time, the plugin generates generated.js in the dist folder.
• When running the application, index.js imports the generated file and executes the function, which prints a dynamic greeting message to the console.

Key Components:

• CodeGenPlugin: Generates the generated.js file.
• Rspack Configuration: Ensures the plugin is executed during the build process.
• Generated Code: Contains the dynamicGreeting function, which is imported and executed at runtime.

This setup allows code generation at build time, with the generated code being injected into the project and executed during runtime.

Running the Example:

1. Clone the repository.
2. Run yarn build to generate the code.
3. Run yarn start to execute the application and see the greeting message in the console.