Enable TypeScript switcher for usePrevious and useWindowSize

Author: gragland

src/pages/usePrevious.md

@@ -4,6 +4,7 @@ title: usePrevious
 date: "2018-11-07"
 gist: https://gist.github.com/gragland/1ed713a68c770ea414c3b92ccf2bdd2f
 sandbox: https://codesandbox.io/s/pwnl6v7z6m
+isMultilingual: true
 ---
 
 One question that comes up a lot is _"When using hooks how do I get the previous value of props or state?"_. With React class components you have the componentDidUpdate method which receives previous props and state as arguments or you can update an instance variable (this.previous = value) and reference it later to get the previous value. So how can we do this inside a functional component that doesn't have lifecycle methods or an instance to store values on? Hooks to the rescue! We can create a custom hook that uses the useRef hook internally for storing the previous value. See the recipe below with inline comments. You can also find this example in the official [React Hooks FAQ](https://reactjs.org/docs/hooks-faq.html#how-to-get-the-previous-props-or-state).

src/pages/useWindowSize.md

@@ -4,6 +4,7 @@ title: useWindowSize
 date: "2018-10-31"
 gist: https://gist.github.com/gragland/4e3d9b1c934a18dc76f585350f97e321
 sandbox: https://codesandbox.io/s/jj61r2w6z5
+isMultilingual: true
 ---
 
 A really common need is to get the current size of the browser window.
@@ -57,13 +58,13 @@ function useWindowSize() {
 }
 ```
 
-```typescript jsx
+```typescript
 import { useState, useEffect } from "react";
 
 // Define general type for useWindowSize hook, which includes width and height
 interface Size {
-  width: number | undefined,
-  height: number | undefined,
+  width: number | undefined;
+  height: number | undefined;
 }
 
 // Usage
@@ -108,4 +109,4 @@ function useWindowSize(): Size {
 
   return windowSize;
 }
-```
+```