Add Access The Latest Lifecycle Methods In An Old App as a react til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_660 TILs and counting..._
+_661 TILs and counting..._
 
 ---
 
@@ -449,6 +449,7 @@ _660 TILs and counting..._
 ### React
 
 - [A Component Is Just A Bag Of Data](react/a-component-is-just-a-bag-of-data.md)
+- [Access The Latest Lifecycle Methods In An Old App](react/access-the-latest-lifecycle-methods-in-an-old-app.md)
 - [Accessing Env Vars In create-react-app](react/accessing-env-vars-in-create-react-app.md)
 - [Alter The Display Name Of A Component](react/alter-the-display-name-of-a-component.md)
 - [Building A React App In The Browser](react/building-a-react-app-in-the-browser.md)

react/access-the-latest-lifecycle-methods-in-an-old-app.md

@@ -0,0 +1,33 @@
+# Access The Latest Lifecycle Methods In An Old App
+
+With the release of React 16.3 we have access to some new lifecycle methods
+and are in the first phase of what will eventually result in the deprecation
+and removal of `componentWillMount`, `componentWillReceiveProps`, and
+`componentWillUpdate`.
+
+You may not be ready to move your project to React 16.3, but that doesn't
+mean you can't start migrating your lifecycle methods now. We'll need a
+polyfill --
+[react-lifecycles-compat](https://github.com/reactjs/react-lifecycles-compat).
+
+```javascript
+import React from 'react';
+import { pollyfill } from 'react-lifecycles-compat';
+
+class MyComponent extends React.Component {
+  static getDerivedStateFromProps(nextProps, prevState) {
+    // ...
+  }
+
+  render() { ... }
+}
+polyfill(MyComponent)
+
+export default MyComponent;
+```
+
+For any of our class components for which we'd like to start using the new
+lifecycle methods, we just need to import the polyfill function and then
+transform the class component with the polyfill before exporting it.
+
+[source](https://reactjs.org/blog/2018/03/27/update-on-async-rendering.html#open-source-project-maintainers)