Merge branch 'bugfix/player' of shaojing/video_player into master

README.md

 
 ```bash
 $ npm run build
+```
+
+
+## Install package.
+
+```bash
+$ npm install https://git.links123.net/links123.com/video_player.git --save
+```
+
+## Usage
+
+```javascript
+import { DefaultPlayer as Video } from 'react-html5video';
+import 'react-html5video/dist/styles.css';
+
+const Player = () => (
+  <Video autoPlay>
+    <source src="demo.mp4" type="video/mp4" />
+  </Video>
+)
 ```

package.json

     "i:demo": "npm run install:demo",
     "test": "jest --env=jsdom",
     "test:watch": "npm run test -- --watch",
+    "prepare": "npm run build",
     "build": "webpack --display-error-details",
     "build:demo": "cd demo && webpack",
     "deploy:demo": "node scripts/deploy:demo.js",

src/video/api.js

  * set. To be primarily used in `mapVideoElToProps`.
  */
 export const togglePause = (videoEl, { paused }) => {
-    if (paused) {
-        videoEl.play();
-        document.querySelector("#videoTitle").style.display = 'none';
-    } else {
-        videoEl.pause();
-        document.querySelector("#videoTitle").style.display = '';
+    const videoTitleEl = document.getElementById("videoTitle")
+
+    paused ? videoEl.play() : videoEl.pause();
+
+    if (videoTitleEl) {
+        videoTitleEl.style.display = paused ? 'none' : '';
     }
 };