Hexo: Use toc() to link undefined

[wanghaijuan]

Environment Info

Node: 8.11.3
Hexo: 3.8.0
Hexo-toc: 1.0.8

For BUG

Error calling method（ <%- toc(page.content, { "class": "toc-nav" }) %> ）link address. Now its structure has become like this:

<ol class="toc-nav">
    <li class="toc-nav-item toc-nav-level-3">
         <a class="toc-nav-link" href="#undefined">
            <span class="toc-nav-number">1.</span> 
            <span class="toc-nav-text">HTML片段展示</span>
         </a>
    </li>
 </ol>

[tcrowe]

For reference this is the part which creates the href:
https://github.com/hexojs/hexo/blob/master/lib/plugins/helper/toc.js#L57

This produces the id:
https://github.com/hexojs/hexo/blob/master/lib/plugins/helper/toc.js#L33

[YoshinoriN]

I will try to update the example.

[gautamz07]

@YoshinoriN , do you guys close issues on here or does the bot detect and close issue..

[YoshinoriN]

@gautamz07
Thank you for following :)

I think it's better to wait for @wanghaijuan replay.
On the other hand, it's better if we update the example.

[wanghaijuan]

I don't know why this bug happened，and I pulled the new one again.

[tcrowe]

@wanghaijuan Why did you close it?

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Also related is this recent PR which changed the toc https://github.com/hexojs/hexo/pull/3404