docs: expand JSONPlaceholder guide with pagination, filtering, and error handling sections

templates/GUIDE.md

@@ -1,5 +1,3 @@
-<main>
-
 ## Guide
 
 You can use JSONPlaceholder with any type of project that needs to get JSON data (React, Vue, Node, Rails, Swift, Android, ...).
@@ -133,6 +131,47 @@ fetch('https://jsonplaceholder.typicode.com/posts/1', {
 
 Important: the resource will not be really deleted on the server but it will be faked as if. 
 
+### Paginate resources
+
+JSONPlaceholder supports pagination through query parameters. You can use any of the following approaches:
+
+#### Using `_limit`
+
+```js
+// Get only the first 5 posts
+fetch('https://jsonplaceholder.typicode.com/posts?_limit=5')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Output: Array of 5 posts (IDs 1-5)
+```
+
+#### Using `_page` with `_limit`
+
+```js
+// Get 5 posts starting from page 2
+fetch('https://jsonplaceholder.typicode.com/posts?_page=2&_limit=5')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Output: Array of 5 posts (IDs 6-10)
+// Formula: returns items from (_page-1) * _limit to _page * _limit
+```
+
+#### Using `_start` and `_end`
+
+```js
+// Get posts from index 10 to 19 (zero-indexed)
+fetch('https://jsonplaceholder.typicode.com/posts?_start=10&_end=20')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Output: Array of 10 posts (IDs 11-20)
+// Note: _start is inclusive, _end is exclusive
+```
+
+You can combine pagination with filters (see below).
+
 ### Filter resources
 
 Basic filtering is supported through query parameters.
@@ -142,17 +181,67 @@ Basic filtering is supported through query parameters.
 fetch('https://jsonplaceholder.typicode.com/posts?userId=1')
   .then(response => response.json())
   .then(json => console.log(json))
+
+// Output: Array of 10 posts (IDs 1-10)
+```
+
+#### Filter case sensitivity
+
+**Important**: Filter parameters are case-sensitive. Using incorrect casing will cause the filter to be ignored and return all results instead of an error.
+
+```js
+// ✓ Correct - returns posts for user 1
+fetch('https://jsonplaceholder.typicode.com/posts?userId=1')
+
+// ✗ Wrong casing - returns ALL 100 posts (filter is silently ignored)
+fetch('https://jsonplaceholder.typicode.com/posts?UserId=1')
+fetch('https://jsonplaceholder.typicode.com/posts?userid=1')
+```
+
+Always use the exact property names as they appear in the resource: `userId`, `id`, `postId`, etc.
+
+#### Combining multiple filters
+
+You can combine multiple filters using `&`. Filters use AND logic (all conditions must match).
+
+```js
+// Get the post with userId=1 AND id=5
+fetch('https://jsonplaceholder.typicode.com/posts?userId=1&id=5')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Output: Single post object with ID 5
+```
+
+#### Combining filters with pagination
+
+```js
+// Get first 3 posts from user 1
+fetch('https://jsonplaceholder.typicode.com/posts?userId=1&_limit=3')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Output: Array of 3 posts (IDs 1-3)
 ```
 
 ### Nested resources
 
-One level of nested route is available.
+One level of nested route is available. Nested routes are equivalent to using query parameters on the related resource.
 
 ```js
-// Equivalent to /comments?postId=1
+// These two requests return identical results:
+
+// Nested route (RESTful style)
 fetch('https://jsonplaceholder.typicode.com/posts/1/comments')
   .then(response => response.json())
   .then(json => console.log(json))
+
+// Query parameter alternative
+fetch('https://jsonplaceholder.typicode.com/comments?postId=1')
+  .then(response => response.json())
+  .then(json => console.log(json))
+
+// Both return: Array of 5 comments for post 1
 ```
 
 Available nested routes:
@@ -163,4 +252,36 @@ Available nested routes:
 * https://jsonplaceholder.typicode.com/users/1/todos
 * https://jsonplaceholder.typicode.com/users/1/posts
 
-</main>
+### Error handling
+
+JSONPlaceholder returns different responses for different error conditions:
+
+#### Invalid resource ID (404)
+
+```js
+// Requesting a post that doesn't exist
+fetch('https://jsonplaceholder.typicode.com/posts/999')
+  .then(response => {
+    console.log(response.status); // 404
+    return response.json();
+  })
+  .then(json => console.log(json))
+
+// Output: {} (empty object)
+```
+
+#### Invalid filter value (200 with empty array)
+
+```js
+// Filtering by a userId that doesn't exist
+fetch('https://jsonplaceholder.typicode.com/posts?userId=999')
+  .then(response => {
+    console.log(response.status); // 200 (not 404)
+    return response.json();
+  })
+  .then(json => console.log(json))
+
+// Output: [] (empty array)
+```
+
+Note: Invalid filter values return a successful response (200) with an empty array, not an error status code.