Add ajax with hooks example (#2803)

* Add ajax with hooks example

* Add comment about empty deps in useEffect hook

* grammar

Co-authored-by: Alex Krolick <[email protected]>

Author: lgordey

content/docs/faq-ajax.md

@@ -82,3 +82,50 @@ class MyComponent extends React.Component {
   }
 }
 ```
+
+Here is the equivalent with [Hooks](https://reactjs.org/docs/hooks-intro.html): 
+
+```js
+function MyComponent() {
+  const [error, setError] = useState(null);
+  const [isLoaded, setIsLoaded] = useState(false);
+  const [items, setItems] = useState([]);
+
+  // Note: the empty deps array [] means
+  // this useEffect will run once
+  // similar to componentDidMount()
+  useEffect(() => {
+    fetch("https://api.example.com/items")
+      .then(res => res.json())
+      .then(
+        (result) => {
+          setIsLoaded(true);
+          setItems(result.items);
+        },
+        // Note: it's important to handle errors here
+        // instead of a catch() block so that we don't swallow
+        // exceptions from actual bugs in components.
+        (error) => {
+          setIsLoaded(true);
+          setError(error);
+        }
+      )
+  }, [])
+
+  if (error) {
+    return <div>Error: {error.message}</div>;
+  } else if (!isLoaded) {
+    return <div>Loading...</div>;
+  } else {
+    return (
+      <ul>
+        {items.map(item => (
+          <li key={item.name}>
+            {item.name} {item.price}
+          </li>
+        ))}
+      </ul>
+    );
+  }
+}
+```