Question
Answer and Explanation
Adding text in front of Rollup typically refers to prepending text to the output of the Rollup bundler. Here are several ways to achieve this, depending on your specific needs and setup:
1. Using Rollup Plugins:
- The most common and recommended approach is to use a Rollup plugin. Plugins allow you to intercept and modify the bundling process. One suitable plugin for this purpose is rollup-plugin-banner or similar plugins that insert banners at the top of the output file.
- First, install the plugin:
npm install rollup-plugin-banner --save-dev
- Then, configure your rollup.config.js file:
import banner from 'rollup-plugin-banner';
export default {
input: 'src/main.js',
output: {
file: 'dist/bundle.js',
format: 'es',
},
plugins: [
banner({
content: '/ This is my custom text at the beginning /',
}),
],
};
- Replace '/ This is my custom text at the beginning /' with your desired text. The `banner` plugin inserts this content at the very beginning of the generated bundle file.
2. Using a Custom Rollup Plugin:
- For more specific or dynamic text, you might create a custom Rollup plugin. Below is an example of a simple custom plugin that prepends static text to the bundle.
// plugins/prependText.js
export default function prependText(options) {
return {
name: 'prepend-text',
renderChunk(code) {
return options.text + code;
},
};
}
- And use it in rollup.config.js:
import prependText from './plugins/prependText.js';
export default {
input: 'src/main.js',
output: {
file: 'dist/bundle.js',
format: 'es',
},
plugins: [
prependText({ text: '// This is a custom prepended text\n' }),
],
};
- This custom plugin prepends the string specified in text to the generated code.
3. Using a Post-Processing Script:
- You can also add text after Rollup is done via a post-processing script within package.json or a custom Node.js script that you can call after Rollup is finished.
- Example using package.json scripts:
"scripts": {
"build": "rollup -c",
"postbuild": "echo '// Custom text added after Rollup' | cat - dist/bundle.js > dist/bundle.temp && mv dist/bundle.temp dist/bundle.js"
}
- This example uses a Unix-based shell command to prepend text to the bundled file after it's generated.
4. Inline Configuration in Rollup Output (Less Recommended):
- While not as flexible as using plugins, you could technically create output formats in Rollup that contain a fixed prepended text. However, this is complex and not intended for such simple tasks. Plugins are generally the best method.
Choosing the Right Approach:
- For simple static text, the `rollup-plugin-banner` is usually the easiest and most common method.
- If you need to handle dynamic content or more complex operations, a custom plugin is better. Post-processing scripts are useful for actions that need to happen after the Rollup process.
- Avoid custom output formats unless there's a very specific reason, and it is generally not recommended for prepending static text.
By understanding and applying these methods, you can successfully add text in front of your Rollup output, tailoring your bundle as needed for your project.