Improve plugin docs

3 files changed, 283 insertions, 306 deletions

diff --git a/docs/bundler/plugins.md b/docs/bundler/plugins.md
index 1cb22432b..2b52ae7da 100644
--- a/docs/bundler/plugins.md
+++ b/docs/bundler/plugins.md
@@ -6,15 +6,17 @@ Bun provides a universal plugin API that can be used to extend both the _runtime
 
 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.
 
+For more complete documentation of the Plugin API, see [Runtime > Plugins](/docs/runtime/plugins).
+
 ## 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#yamlPlugin.ts
+```tsx#myPlugin.ts
 import type { BunPlugin } from "bun";
 
 const myPlugin: BunPlugin = {
-  name: "YAML loader",
+  name: "Custom loader",
   setup(build) {
     // implementation
   },
@@ -30,307 +32,3 @@ Bun.build({
   plugins: [myPlugin],
 });
 ```
-
-<!-- It can also be "registered" with the Bun runtime using the `Bun.plugin()` function. Once registered, the currently executing `bun` process will incorporate the plugin into its module resolution algorithm.
-
-```ts
-import {plugin} from "bun";
-
-plugin(myPlugin);
-``` -->
-
-## `--preload`
-
-To consume this plugin, add this file to 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 = ["./yamlPlugin.ts"]
-```
-
-To preload files during `bun test`:
-
-```toml
-[test]
-preload = ["./loader.ts"]
-```
-
-{% details summary="Usage without preload" %}
-
-Alternatively, you can import this file manually at the top of your project's entrypoint, before any application code is imported.
-
-```ts#app.ts
-import "./yamlPlugin.ts";
-import { config } from "./config.yml";
-
-console.log(config);
-```
-
-{% /details %}
-
-## 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
-  }),
-);
-
-// application code
-```
-
-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());
-
-import { renderToStaticMarkup } from "react-dom/server";
-import Foo from "./bar.mdx";
-console.log(renderToStaticMarkup(<Foo />));
-```
-
-## Loaders
-
-<!-- The plugin logic is implemented in the `setup` function using the builder provided as the first argument (`build` in the example above). The `build` variable provides two methods: `onResolve` and `onLoad`. -->
-
-<!-- ## `onResolve` -->
-
-<!-- The `onResolve` method lets you intercept imports that match a particular regex and modify the resolution behavior, such as re-mapping the import to another file. In the simplest case, you can simply remap the matched import to a new path.
-
-```ts
-import { plugin } from "bun";
-
-plugin({
-  name: "YAML loader",
-  setup(build) {
-    build.onResolve();
-    // implementation
-  },
-});
-``` -->
-
-<!--
-Internally, Bun's transpiler automatically turns `plugin()` calls into separate files (at most 1 per file). This lets loaders activate before the rest of your application runs with zero configuration. -->
-
-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";
-
-await 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`.
diff --git a/docs/nav.ts b/docs/nav.ts
index ff74e16c3..4b3a67ec0 100644
--- a/docs/nav.ts
+++ b/docs/nav.ts
@@ -110,6 +110,9 @@ export default {
     page("runtime/nodejs-apis", "Node.js compatibility", {
       description: `Bun aims for full Node.js compatibility. This page tracks the current compatibility status.`,
     }),
+    page("runtime/plugins", "Plugins", {
+      description: `Implement custom loaders and module resolution logic with Bun's plugin system.`,
+    }),
 
     // page("runtime/nodejs", "Node.js compatibility", {
     //   description: `Track the status of Bun's API compatibility with Node.js.`,
diff --git a/docs/runtime/plugins.md b/docs/runtime/plugins.md
new file mode 100644
index 000000000..39eea3278
--- /dev/null
+++ b/docs/runtime/plugins.md
@@ -0,0 +1,276 @@
+{% callout %}
+**Note** — Introduced in Bun v0.1.11.
+{% /callout %}
+
+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";
+
+await 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`.