docs: YAML plugin lesson updates (#12)

src/content/tutorial/vite-plugin/yaml-plugin/defining-custom-plugin/content.md

@@ -1,17 +1,17 @@
 ---
 type: lesson
-title: Defining custom plugin
+title: Defining a custom plugin
 focus: /vite.config.ts
 ---
 
-# Defining custom plugin
+# Defining a custom plugin
 
-Plugins can have various properties that are listed in [Plugin API | Vite](https://vitejs.dev/guide/api-plugin.html) documentation. The only **required property** is `name`.
+A plugin is a plain object that defines hooks to modify the way Vite resolves ids, loads and transforms modules, and more. It can have various properties that are listed in the [Plugin API | Vite](https://vitejs.dev/guide/api-plugin.html) documentation. The only **required property** is `name`.
 
-Let's start by adding a custom plugin in our Vite configuration. To do this, add a new `plugins` property into the Vite configuration. The `plugins` should be an array.
+Let's start by adding a custom plugin in our Vite config file. To do this, add a new `plugins` array property in the exported config object.
 
-Inside the `plugins` array, define a new object with `name` `'yaml-plugin'`.
+Then, let's add a new object with `name` `'yaml-plugin'` inside the `plugins` array.
 
-Successfully defined plugin should be reported in the Preview tab:
+A successfully defined plugin should be reported in the Preview tab:
 
 > Loaded Vite plugins: yaml-plugin ✅

src/content/tutorial/vite-plugin/yaml-plugin/defining-load-hook/content.md

@@ -1,10 +1,10 @@
 ---
 type: lesson
-title: Defining load hook
+title: Defining the load hook
 focus: /vite.config.ts
 ---
 
-# Defining load hook
+# Defining the load hook
 
 Next we'll need to intercept loading of `.yaml` files. Let's start by adding a [`load`](https://rollupjs.org/plugin-development/#load) hook in our Vite plugin.
 
@@ -16,7 +16,7 @@ Next we'll need to intercept loading of `.yaml` files. Let's start by adding a [
 }
 ```
 
-Vite will call this hook with all the loaded files. As our plugin is only interested in `.yaml` files, we can check `id` for this extension.
+Vite will call the load hook of every plugin for each resolved id to the load the module code. A load hook can return custom code for an id, or skip it by to let other plugins handle it. As our plugin is only interested in `.yaml` files, we can check `id` for this extension. 
 
 ```js
 {
@@ -29,7 +29,7 @@ Vite will call this hook with all the loaded files. As our plugin is only intere
 }
 ```
 
-Our `load` function should return an object with `code` property. This property should contain the actual code that importing this specific `.yaml` file should produce. As we don't yet know how to convert `.yaml` files into Javascript, we can return something simpler here.
+Our `load` function should return an object with a `code` property for these ids. This property should contain the actual code that importing this specific `.yaml` file should produce. As we don't yet know how to convert `.yaml` files into JavaScript, let's return a simple module that exports a default string first:
 
 ```js
 {

src/content/tutorial/vite-plugin/yaml-plugin/importing-yaml-files/content.md

@@ -4,13 +4,13 @@ title: Importing YAML files
 focus: /index.js
 ---
 
-# Welcome to Vite Plugin tutorial
+# Welcome to the Vite Plugin API tutorial
 
-Hey there, and welcome to Vite Plugin tutorial 👋!
+Hey there, and welcome to the Vite Plugin API tutorial 👋!
 
-In this tutorial we'll go through steps for creating custom Vite plugins. We'll start by creating a custom Vite plugin for loading `.yaml` files.
+We'll create custom Vite plugins step by step, starting with a custom Vite plugin for loading `.yaml` files.
 
-Our goal is to be able to import `content.yaml` file in a Javascript file and use it as plain Javascript object.
+Our goal is to be able to import a `content.yaml` file in a module and use it as plain JavaScript object:
 
 ```js [index.js]
 import content from "./content.yaml";
@@ -19,7 +19,7 @@ console.log(content);
 // > [{  employees: [{ id: 1, ... }, ...], projects: [{ id: 101, ...}, ...] }]
 ```
 
-Try doing this in `index.js`:
+Starting with the content as a variable in `index.js`, try changing the code to import it from the YAML file instead:
 
 ```js [index.js] add={1} del={2}
 import content from "./content.yaml";
@@ -28,4 +28,4 @@ const content = ["Initial content"];
 export default content;
 ```
 
-At this point we should run into error when Vite fails to load `.yaml` file. ❌
+We should run into an error when Vite fails to load `.yaml` file. ❌

src/content/tutorial/vite-plugin/yaml-plugin/processing-yaml-files/content.md

@@ -6,10 +6,10 @@ focus: /vite.config.ts
 
 # Processing YAML files
 
-Our Vite plugin can now recognize `.yaml` files that are being loaded. Next we'll need to add logic for converting the `.yaml` files into Javascript and pass the output from `load` hook.
+Our Vite plugin can now properly intercept `.yaml` files that are being loaded. Next we'll need to add logic for converting the `.yaml` files into JavaScript and return that as the output of our `load` hook.
 
-To get the content of requested file we'll need to use [`readFileSync`](https://nodejs.org/api/fs.html#fsreadfilesyncpath-options) method from `node:fs`.
-We can convert the YAML content into Javascript using [`yaml`](https://www.npmjs.com/package/yaml) package. It has a `parse()` function that takes YAML content as `string`.
+To get the content of requested file we can use [`readFileSync`](https://nodejs.org/api/fs.html#fsreadfilesyncpath-options) method from `node:fs`.
+We can convert the YAML content into JavaScript using the [`yaml`](https://www.npmjs.com/package/yaml) npm package. It has a `parse()` function that takes YAML content as `string` and returns a JavaScript object.
 
 ```ts
 import { readFileSync } from "node:fs";
@@ -20,18 +20,18 @@ const yaml = parse(content);
 //    ^^^^ [{ employees: [{ id: 1, ...}, ...], projects: [{ id: 101, ...}] }]
 ```
 
-The `yaml` variable now holds a Javascript object that represents our `content.yaml` contents. To return this from `load` hook, we'll need to serialize it to string with [`JSON.stringify`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify):
+The `yaml` variable now holds an object that represents our `content.yaml` contents. To return this from the `load` hook, we'll need to serialize it to a string with [`JSON.stringify`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify):
 
 ```ts
 return {
   code: `export default ${JSON.stringify(yaml)}`
 };
 ```
 
-Add required logic to Vite plugin's load hook:
+Add the required logic to Vite plugin's load hook:
 
-- Read requested file from file system using `readFileSync` (filename is in `id` variable)
-- Convert contents of `.yaml` file into Javascript using `parse` from `yaml` package
-- Serialize the Javascript object into `string` and return it as default export from the `load` hook
+- Read requested file from file system using `readFileSync` (the filename is the `id` parameter).
+- Convert contents of `.yaml` file into Javascript using `parse` from `yaml` package.
+- Serialize the JavaScript object into a `string` and return it as the default export of a module from the `load` hook.
 
-Contents of `content.yaml` should appear in preview as JSON. ✅
+The contents of `content.yaml` should appear in the preview as JSON. ✅

src/content/tutorial/vite-plugin/yaml-plugin/summarize-yaml-plugin/content.md

@@ -6,7 +6,7 @@ focus: /vite.config.ts
 
 # Summary
 
-Our custom Vite plugin can now intercept `*.yaml` file imports and convert them into Javascript.
+Our custom Vite plugin can now intercept `*.yaml` file imports and load them as JavaScript modules.
 
 Before you head on to create your own plugins for loading some other non-Javascript files, let's summarize what we've done:
 
@@ -25,3 +25,5 @@ Before you head on to create your own plugins for loading some other non-Javascr
 </ol>
 
 📚 Homework: Build a Vite plugin that can import [`.csv` files](https://en.wikipedia.org/wiki/Comma-separated_values) directly into Javascript. You can even build your own minimal CSV-parser!
+
+Tip: Before creating your own plugin, search for popular Vite or compatible Rollup plugins. For YAML support, you can directly add the official [@rollup/plugin-yaml](https://www.npmjs.com/package/@rollup/plugin-yaml) to your Vite config.