add transition TS types and prop-types, reflect changes in readme, update snapshot

Author: Lasse Borly

.size-snapshot.json

@@ -1,11 +1,11 @@
 {
   "dist/addons.umd.js": {
-    "bundled": 16003,
+    "bundled": 16024,
     "minified": 5898,
     "gzipped": 2150
   },
   "dist/web.umd.js": {
-    "bundled": 86075,
+    "bundled": 86161,
     "minified": 35541,
     "gzipped": 12021
   }

index.d.ts

@@ -162,9 +162,15 @@ interface TransitionProps<S extends object, DS extends object = {}> {
    */
   items?: Array<TransitionItemProps> | TransitionItemProps
 
-  children?: SpringRendererFunc<S, DS> | Array<SpringRendererFunc<S, DS>>
-
-  render?: SpringRendererFunc<S, DS> | Array<SpringRendererFunc<S, DS>>
+  children?:
+    | SpringRendererFunc<S, DS>
+    | Array<SpringRendererFunc<S, DS>>
+    | boolean
+
+  render?:
+    | SpringRendererFunc<S, DS>
+    | Array<SpringRendererFunc<S, DS>>
+    | boolean
 }
 
 export class Transition<

readme.md

@@ -15,14 +15,14 @@ import { Spring, ... } from 'react-spring/dist/universal'
 
 # Table of Contents 👇
 
-* [What is it?](#what-is-it-)
-* [Why do we need yet another?](#why-do-we-need-yet-another-)
-* [Links](#links-)
-* [Basic overview](#basic-overview-)
-* [Interpolation](#interpolation-)
-* [Render props](#render-props-)
-* [Native rendering](#native-rendering-)
-* [React-native and other targets](#react-native-and-other-targets-)
+- [What is it?](#what-is-it-)
+- [Why do we need yet another?](#why-do-we-need-yet-another-)
+- [Links](#links-)
+- [Basic overview](#basic-overview-)
+- [Interpolation](#interpolation-)
+- [Render props](#render-props-)
+- [Native rendering](#native-rendering-)
+- [React-native and other targets](#react-native-and-other-targets-)
 
 # What is it? 🤔
 
@@ -68,7 +68,6 @@ react-spring builds upon animated's foundation, making it leaner and more flexib
 
 For a more detailed explanation read [Why React needed yet another animation library](https://medium.com/@drcmda/why-react-needed-yet-another-animation-library-introducing-react-spring-8212e424c5ce).
 
-
 # Links 🔗
 
 #### [Examples and Codesandboxes](https://github.com/drcmda/react-spring/blob/master/examples)
@@ -127,11 +126,22 @@ Given a single child instead of a list you can toggle between two components.
 import { Transition } from 'react-spring'
 
 <Transition from={{ opacity: 0 }} enter={{ opacity: 1 }} leave={{ opacity: 0 }}>
-    {toggle ? ComponentA : ComponentB}
+    {toggle
+        ? styles => <ComponentA style={styles} />
+        : styles => <ComponentB style={styles} />
+    }
 </Transition>
 ```
 
-If you need to toggle a single child, that is also possible: `{toggle && Component}`
+If you need to toggle a single child, that is also possible.
+
+```jsx
+import { Transition } from 'react-spring'
+
+<Transition from={{ opacity: 0 }} enter={{ opacity: 1 }} leave={{ opacity: 0 }}>
+    {visible && (styles => <SingleComponent style={styles} />)}
+</Transition>
+```
 
 #### Trails and staggered animations ([Demo](https://codesandbox.io/embed/vvmv6x01l5))
 
@@ -279,7 +289,6 @@ const AnimatedView = animated(View)
 This project exists thanks to all the people who contribute. [[Contribute]](CONTRIBUTING.md).
 <a href="graphs/contributors"><img src="https://opencollective.com/react-spring/contributors.svg?width=890" /></a>
 
-
 # Backers
 
 Thank you to all our backers! 🙏 [[Become a backer](https://opencollective.com/react-spring#backer)]

src/Transition.js

@@ -52,10 +52,12 @@ export default class Transition extends React.PureComponent {
     children: PropTypes.oneOfType([
       PropTypes.arrayOf(PropTypes.func),
       PropTypes.func,
+      PropTypes.bool,
     ]),
     render: PropTypes.oneOfType([
       PropTypes.arrayOf(PropTypes.func),
       PropTypes.func,
+      PropTypes.bool,
     ]),
   }