async support

[pod4g]

I define a special markdown syntax for our editor

the syntas like this:

```sku
1120
```

the number is a id， I should fetch data by ajax (http://x.x.x.x/?id=1120)， and then i will convert the data to html , but marked not support async

What should I do?

I think this solution is pretty good #798

Relevant issues: #458

thanks for any reply !

[pod4g]

the ajax returned data like this:

{
 title: '天王盖地虎，宝塔震河妖',
 image: '//content.image.alimmdn.com/sku/1463573933Q3cRJL_jpg.jpeg',
 price: '￥250'
}

convert the data to html：

<div class="sku-card">
  <h1 class="sku-title">天王盖地虎，宝塔震河妖</h1>
  <img src="//content.image.alimmdn.com/sku/1463573933Q3cRJL_jpg.jpeg">
  <span class="sku-price">￥250</span>
</div>

[Feder1co5oave]

You should override the code renderer in such a way that whenever lang == 'sku' you should return a <script> element whose code somehow performs the ajax request and then document.writes the content into the page.

[joshbruce]

Alternatively, you should be able to do it after the build. Seems like we are trying to make Markdown (and Marked) do more than it was intented to - convert Markdown to HTML based on specifications.

  ```sku
  1120
    ```

  Becomes something like this
  <code><pre>...</pre></code>

Might be more reasonable to do something like:

...markdown, markdown, markdown

<div class="sku-card" data-sku="1120"></div>

...markdown, markdown, markdown

Once the HTML is rendered, run the JS selector for data-sku - perform AJAX/J and build internals HTML. Also, for semantic HTML purposes may want to consider a different header level, or using an <article> for each sku-card instead of the div...so, if you're feeling particularly daring (and possible semantically incorrect).

<article is="sku-card" data-sku="1120"></article>

Becomes:

<article is="sku-card" data-sku="1120">
  <h1>...</h1>
  <img>
  <span>...</span>
</article>

You shouldn't need the extra classes because the wrapper says what you're playing with. If you use those components outside of the sku-card, then by all means continue using the classes or faux object inheritance.

Closing.