mirror of
https://github.com/oven-sh/bun
synced 2026-02-10 02:48:50 +00:00
273 lines
7.1 KiB
Markdown
273 lines
7.1 KiB
Markdown
Bun provides a universal plugin API that can be used to extend both the _runtime_ and [_bundler_](/docs/bundler).
|
|
|
|
Plugins intercept imports and perform custom loading logic: reading files, transpiling code, etc. They can be used to add support for additional file types, like `.scss` or `.yaml`. In the context of Bun's bundler, plugins can be used to implement framework-level features like CSS extraction, macros, and client-server code co-location.
|
|
|
|
## Usage
|
|
|
|
A plugin is defined as simple JavaScript object containing a `name` property and a `setup` function. Register a plugin with Bun using the `plugin` function.
|
|
|
|
```tsx#myPlugin.ts
|
|
import { plugin, type BunPlugin } from "bun";
|
|
|
|
const myPlugin: BunPlugin = {
|
|
name: "Custom loader",
|
|
setup(build) {
|
|
// implementation
|
|
},
|
|
};
|
|
```
|
|
|
|
Plugins have to be registered before any other code runs! To achieve this, use the `preload` option in your [`bunfig.toml`](/docs/runtime/configuration). Bun automatically loads the files/modules specified in `preload` before running a file.
|
|
|
|
```toml
|
|
preload = ["./myPlugin.ts"]
|
|
```
|
|
|
|
To preload files before `bun test`:
|
|
|
|
```toml
|
|
[test]
|
|
preload = ["./myPlugin.ts"]
|
|
```
|
|
|
|
## Third-party plugins
|
|
|
|
By convention, third-party plugins intended for consumption should export a factory function that accepts some configuration and returns a plugin object.
|
|
|
|
```ts
|
|
import { plugin } from "bun";
|
|
import fooPlugin from "bun-plugin-foo";
|
|
|
|
plugin(
|
|
fooPlugin({
|
|
// configuration
|
|
}),
|
|
);
|
|
```
|
|
|
|
Bun's plugin API is based on [esbuild](https://esbuild.github.io/plugins). Only [a subset](/docs/bundler/vs-esbuild#plugin-api) of the esbuild API is implemented, but some esbuild plugins "just work" in Bun, like the official [MDX loader](https://mdxjs.com/packages/esbuild/):
|
|
|
|
```jsx
|
|
import { plugin } from "bun";
|
|
import mdx from "@mdx-js/esbuild";
|
|
|
|
plugin(mdx());
|
|
```
|
|
|
|
## Loaders
|
|
|
|
Plugins are primarily used to extend Bun with loaders for additional file types. Let's look at a simple plugin that implements a loader for `.yaml` files.
|
|
|
|
```ts#yamlPlugin.ts
|
|
import { plugin } from "bun";
|
|
|
|
plugin({
|
|
name: "YAML",
|
|
async setup(build) {
|
|
const { load } = await import("js-yaml");
|
|
const { readFileSync } = await import("fs");
|
|
|
|
// when a .yaml file is imported...
|
|
build.onLoad({ filter: /\.(yaml|yml)$/ }, (args) => {
|
|
|
|
// read and parse the file
|
|
const text = readFileSync(args.path, "utf8");
|
|
const exports = load(text) as Record<string, any>;
|
|
|
|
// and returns it as a module
|
|
return {
|
|
exports,
|
|
loader: "object", // special loader for JS objects
|
|
};
|
|
});
|
|
},
|
|
});
|
|
```
|
|
|
|
With this plugin, data can be directly imported from `.yaml` files.
|
|
|
|
{% codetabs %}
|
|
|
|
```ts#index.ts
|
|
import "./yamlPlugin.ts"
|
|
import {name, releaseYear} from "./data.yml"
|
|
|
|
console.log(name, releaseYear);
|
|
```
|
|
|
|
```yaml#data.yml
|
|
name: Fast X
|
|
releaseYear: 2023
|
|
```
|
|
|
|
{% /codetabs %}
|
|
|
|
Note that the returned object has a `loader` property. This tells Bun which of its internal loaders should be used to handle the result. Even though we're implementing a loader for `.yaml`, the result must still be understandable by one of Bun's built-in loaders. It's loaders all the way down.
|
|
|
|
In this case we're using `"object"`—a built-in loader (intended for use by plugins) that converts a plain JavaScript object to an equivalent ES module. Any of Bun's built-in loaders are supported; these same loaders are used by Bun internally for handling files of various kinds. The table below is a quick reference; refer to [Bundler > Loaders](/docs/bundler/loaders) for complete documentation.
|
|
|
|
{% table %}
|
|
|
|
- Loader
|
|
- Extensions
|
|
- Output
|
|
|
|
---
|
|
|
|
- `js`
|
|
- `.mjs` `.cjs`
|
|
- Transpile to JavaScript files
|
|
|
|
---
|
|
|
|
- `jsx`
|
|
- `.js` `.jsx`
|
|
- Transform JSX then transpile
|
|
|
|
---
|
|
|
|
- `ts`
|
|
- `.ts` `.mts` `cts`
|
|
- Transform TypeScript then transpile
|
|
|
|
---
|
|
|
|
- `tsx`
|
|
- `.tsx`
|
|
- Transform TypeScript, JSX, then transpile
|
|
|
|
---
|
|
|
|
- `toml`
|
|
- `.toml`
|
|
- Parse using Bun's built-in TOML parser
|
|
|
|
---
|
|
|
|
- `json`
|
|
- `.json`
|
|
- Parse using Bun's built-in JSON parser
|
|
|
|
---
|
|
|
|
- `napi`
|
|
- `.node`
|
|
- Import a native Node.js addon
|
|
|
|
---
|
|
|
|
- `wasm`
|
|
- `.wasm`
|
|
- Import a native Node.js addon
|
|
|
|
---
|
|
|
|
- `object`
|
|
- _none_
|
|
- A special loader intended for plugins that converts a plain JavaScript object to an equivalent ES module. Each key in the object corresponds to a named export.
|
|
|
|
{% /callout %}
|
|
|
|
Loading a YAML file is useful, but plugins support more than just data loading. Let's look at a plugin that lets Bun import `*.svelte` files.
|
|
|
|
```ts#sveltePlugin.ts
|
|
import { plugin } from "bun";
|
|
|
|
plugin({
|
|
name: "svelte loader",
|
|
async setup(build) {
|
|
const { compile } = await import("svelte/compiler");
|
|
const { readFileSync } = await import("fs");
|
|
|
|
// when a .svelte file is imported...
|
|
build.onLoad({ filter: /\.svelte$/ }, ({ path }) => {
|
|
|
|
// read and compile it with the Svelte compiler
|
|
const file = readFileSync(path, "utf8");
|
|
const contents = compile(file, {
|
|
filename: path,
|
|
generate: "ssr",
|
|
}).js.code;
|
|
|
|
// and return the compiled source code as "js"
|
|
return {
|
|
contents,
|
|
loader: "js",
|
|
};
|
|
});
|
|
},
|
|
});
|
|
```
|
|
|
|
> Note: in a production implementation, you'd want to cache the compiled output and include additional error handling.
|
|
|
|
The object returned from `build.onLoad` contains the compiled source code in `contents` and specifies `"js"` as its loader. That tells Bun to consider the returned `contents` to be a JavaScript module and transpile it using Bun's built-in `js` loader.
|
|
|
|
With this plugin, Svelte components can now be directly imported and consumed.
|
|
|
|
```js
|
|
import "./sveltePlugin.ts";
|
|
import MySvelteComponent from "./component.svelte";
|
|
|
|
console.log(mySvelteComponent.render());
|
|
```
|
|
|
|
## Reading the config
|
|
|
|
Plugins can read and write to the [build config](/docs/bundler#api) with `build.config`.
|
|
|
|
```ts
|
|
Bun.build({
|
|
entrypoints: ["./app.ts"],
|
|
outdir: "./dist",
|
|
sourcemap: "external",
|
|
plugins: [
|
|
{
|
|
name: "demo",
|
|
setup(build) {
|
|
console.log(build.config.sourcemap); // "external"
|
|
|
|
build.config.minify = true; // enable minification
|
|
|
|
// `plugins` is readonly
|
|
console.log(`Number of plugins: ${build.config.plugins.length}`);
|
|
},
|
|
},
|
|
],
|
|
});
|
|
```
|
|
|
|
## Reference
|
|
|
|
```ts
|
|
namespace Bun {
|
|
function plugin(plugin: {
|
|
name: string;
|
|
setup: (build: PluginBuilder) => void;
|
|
}): void;
|
|
}
|
|
|
|
type PluginBuilder = {
|
|
onResolve: (
|
|
args: { filter: RegExp; namespace?: string },
|
|
callback: (args: { path: string; importer: string }) => {
|
|
path: string;
|
|
namespace?: string;
|
|
} | void,
|
|
) => void;
|
|
onLoad: (
|
|
args: { filter: RegExp; namespace?: string },
|
|
callback: (args: { path: string }) => {
|
|
loader?: Loader;
|
|
contents?: string;
|
|
exports?: Record<string, any>;
|
|
},
|
|
) => void;
|
|
config: BuildConfig;
|
|
};
|
|
|
|
type Loader = "js" | "jsx" | "ts" | "tsx" | "json" | "toml" | "object";
|
|
```
|
|
|
|
The `onLoad` method optionally accepts a `namespace` in addition to the `filter` regex. This namespace will be be used to prefix the import in transpiled code; for instance, a loader with a `filter: /\.yaml$/` and `namespace: "yaml:"` will transform an import from `./myfile.yaml` into `yaml:./myfile.yaml`.
|