# parcel-plugin-codegen
[](https://www.npmjs.com/package/parcel-plugin-codegen)
[](https://github.com/FlorianRappl/codegen-js/releases)
[](https://github.com/FlorianRappl/codegen-js/issues)
A plugin for Parcel to allow bundle-time asset generation. This can be useful to work efficiently with established conventions and reduce duplication and boilerplate code.
## Usage
Just install the plugin. In any file reference a `.codegen` file, e.g., in a TypeScript asset
```js
const generatedModule = require('./my.codegen');
```
Create a `.codegen` file with the structure:
```js
module.exports = function() {
return `module.exports = {}`;
};
```
### Async Generation
You can also use promises in your code generation. As an example, if your `.codegen` file looks similar to this:
```js
module.exports = function() {
return callSomeApi().then(result => `module.exports = ${JSON.stringify(result)}`);
};
```
The new asset will be created asynchronously. Furthermore, you can obviously use `require` or `import` directly in your generated code. Since the asset will be run through Parcel like any other asset, you can use this mechanism to include files from a directory without referencing them explicitly:
```js
module.exports = function() {
return `
const { lazy } = require('react');
module.exports = lazy(() => import(${JSON.stringify(filePath)}));
`;
};
```
### Asset Type Declaration
By default, the type of the generated asset will be a JS module. However, you could also generate, e.g., an HTML file:
```js
module.exports = function() {
return `Hi Mum!
`;
};
module.exports.type = 'html';
```
Make sure that the type you return is understood by Parcel. It will be further processed (as such you could also generate, e.g., `ts` assets).
Alternatively, you can return an object using the following structure:
```js
module.exports = function() {
return {
value: `Hi Mum!
`,
type: 'html',
};
};
```
The latter is especially handy when the `type` is not fixed or will be determined via an async operation.
## License
This plugin is released using the MIT license. For more information see the [LICENSE file](./LICENSE).