title: How to write diff code with syntax highlight in Github
body: <p>Github supports syntax highlight as follows:</p>
  
  <pre><code>```javascript
  let message = 'hello world!'
  ```
  </code></pre>
  
  <p>And it supports diff as follows: (but WITHOUT syntax highlight)</p>
  
  <pre><code>```diff
  -let message = 'hello world!'
  +let message = 'hello stackoverflow!'
  ```
  </code></pre>
  
  <p>How can I get both 'syntax hightlight' AND 'diff' ?</p>