概述
大多数使用 Markdown 的人会发现基础语法和扩展语法可以满足他们的需求。 但很有可能，如果你使用 Markdown 的时间足够长，你会不可避免地发现它不支持你需要的东西。此页面提供了解决 Markdown 限制的提示和技巧。
下划线
划线文本不是你通常在网络写作中看到的，可能是因为带下划线的文本几乎是链接的同义词。但是，如果你正在撰写论文或报告，你可能需要能够在单词和短语下划线。 熊掌记 和 Simplenote 等一些应用程序提供了对文本下划线的支持，但 Markdown 本身并不支持下划线。 如果你的 Markdown 处理器支持 HTML, ，你可以使用 <ins> HTML 标签为文档中的文本添加下划线。
Some of these words <ins>will be underlined</ins>.
渲染输出如下所示：
Some of these words will be underlined.
缩进 (Tab)
Tabs and whitespace have a special meaning in Markdown. You can use trailing whitespace to create line breaks, and you can use tabs to create code blocks. But what if you need to indent a paragraph the old-fashioned way, using the tab key? Markdown doesn’t provide an easy way of doing that.
Your best bet might be to use a Markdown editor that supports indentation. This is common in applications that are more oriented towards desktop publishing. For example, iA Writer allows you to customize indentation settings for the editor in the application preferences. It also provides template customization options so that you can make the rendered document look the way you expect it to, indentation and all.
Another option, if your Markdown processor supports HTML, is to use the HTML entity for non-breaking space ( ). This should probably be your option of last resort as it can get awkward. Basically, every in your Markdown source will be replaced with a space in the 渲染输出. So if you stick four instances of before a paragraph, the paragraph will look like it’s indented four spaces.
This is the first sentence of my indented paragraph.
渲染输出看起来是这样的：
This is the first sentence of my indented paragraph.
Center
Having the ability to center text is a necessity when writing a paper or a report. Unfortunately, Markdown doesn’t have any concept of text alignment (one possible exception is when using tables). The good news is that there’s an HTML tag you can use: <center>. If your Markdown processor supports HTML, you can place these tags around whatever text you want to center align.
<center>This text is centered.</center>
渲染输出看起来是这样的：
This text is centered.
The <center> HTML tag is technically supported but officially deprecated, which means it works for now but you’re not supposed to be using it. Unfortunately, there’s not another pure HTML alternative. You could try using one of the CSS alternatives. Not all Markdown applications provide CSS support, but if the one you’re using does, here’s an alternative to the <center> tag:
<p style="text-align:center">Center this text</p>
If this is supported by your Markdown application, the output looks like this:
Center this text
Color
Markdown doesn’t allow you to change the color of text, but if your Markdown processor supports HTML, you can use the <font> HTML tag. The color attribute allows you to specify the font color using a color’s name or the hexadecimal #RRGGBB code.
<font color="red">This text is red!</font>
渲染输出看起来是这样的：
This text is red!
The <font> HTML tag is technically supported but officially deprecated, which means it works for now but you’re not supposed to be using it. Unfortunately, there’s not another pure HTML alternative. You could try using one of the CSS alternatives. Not all Markdown applications provide CSS support, but if the one you’re using does, here’s an alternative to the <font> tag:
<p style="color:blue">Make this text blue.</p>
If this is supported by your Markdown application, the output looks like this:
Make this text blue.
Comments
Some people need the ability to write sentences in their Markdown files that will not appear in the 渲染输出. These comments are essentially hidden text. The text is viewable by the author of the document, but it’s not printed on the webpage or PDF. Markdown doesn’t natively support comments, but several enterprising individuals have devised a solution.
To add a comment, place text inside brackets followed by a colon, a space, and a pound sign (e.g., [comment]: #). You should put blank lines before and after a comment.
Here's a paragraph that will be visible.
[This is a comment that will be hidden.]: #
And here's another paragraph that's visible.
渲染输出看起来是这样的：
Here’s a paragraph that will be visible.
And here’s another paragraph that’s visible.
Admonitions
Admonitions are frequently used in documentation to call attention to warnings, notes, and tips. Markdown doesn’t provide special syntax for admonitions, and most Markdown applications don’t provide support for admonitions (one exception is MkDocs).
However, if you need to add admonitions, you might be able to use blockquotes with emoji and emphasis to create something that looks similar to the admonitions you see on other websites.
> :warning: **Warning:** Do not push the big red button.
> :memo: **Note:** Sunrises are beautiful.
> :bulb: **Tip:** Remember to appreciate the little things in life.
渲染输出看起来是这样的：
⚠️ Warning: Do not push the big red button.
📝 Note: Sunrises are beautiful.
💡 Tip: Remember to appreciate the little things in life.
Image Size
The Markdown syntax for images doesn’t allow you to specify the width and height of images. If you need to resize an image and your Markdown processor supports HTML, you can use the img HTML tag with the width and height attributes to set the dimensions of an image in pixels.
<img src="image.png" width="200" height="100">
The 渲染输出 will contain the image resized to the dimensions you specified.
Image Captions
Markdown doesn’t natively support image captions, but there are two possible workarounds. If your Markdown application supports HTML, you can use the figure and figcaption HTML tags to add a caption for your image.
<figure>
<img src="/assets/images/albuquerque.jpg"
alt="Albuquerque, New Mexico">
<figcaption>A single track trail outside of Albuquerque, New Mexico.</figcaption>
</figure>
渲染输出看起来是这样的：
If your Markdown application doesn’t support HTML, you could try placing the caption directly below the image and using emphasis.
*A single track trail outside of Albuquerque, New Mexico.*
渲染输出看起来是这样的：
A single track trail outside of Albuquerque, New Mexico.
Link Targets
Some people like creating links that open in new tabs or windows. The Markdown syntax for links doesn’t allow you to specify the target attribute, but if your Markdown processor supports HTML, you can use HTML to create these links.
<a href="https://www.markdownguide.org" target="_blank">Learn Markdown!</a>
渲染输出看起来是这样的：
Symbols
Markdown doesn’t provide special syntax for symbols. However, in most cases, you can copy and paste whatever symbol you want to use into your Markdown document. For example, if you need to display Pi (π), just find the symbol on a webpage and copy and paste it into your document. The symbol should appear as expected in the 渲染输出.
Alternatively, if your Markdown application supports HTML, you can use the HTML entity for whatever symbol you want to use. For example, if you want to display the copyright sign (©), you can copy and paste the HTML entity for copyright (©) into your Markdown document.
Here’s a partial list of HTML entities for symbols:
- Copyright (©) —
© - Registered trademark (®) —
® - Trademark (™) —
™ - Euro (€) —
€ - Left arrow (←) —
← - Up arrow (↑) —
↑ - Right arrow (→) —
→ - Down arrow (↓) —
↓ - Degree (°) —
° - Pi (π) —
π
For a complete list of available HTML entities, refer to Wikipedia’s page on HTML entities.
Table Formatting
Markdown tables are notoriously finicky. You can’t use many Markdown syntax elements to format the text in table cells. But there are workarounds for at least two common table issues: Line breaks and lists.
Line Breaks Within Table Cells
You can separate paragraphs within a table cell by using one or more <br> HTML tags.
| Syntax | Description |
| ----------- | ----------- |
| Header | Title |
| Paragraph | First paragraph. <br><br> Second paragraph. |
渲染输出看起来是这样的：
| Syntax | Description |
|---|---|
| Header | Title |
| Paragraph | First paragraph. Second paragraph. |
Lists Within Table Cells
You can add a list within a table cell by using HTML tags.
| Syntax | Description |
| ----------- | ----------- |
| Header | Title |
| List | Here's a list! <ul><li>Item one.</li><li>Item two.</li></ul> |
渲染输出看起来是这样的：
| Syntax | Description |
|---|---|
| Header | Title |
| List | Here's a list!
|
Table of Contents
Some Markdown applications like Markdeep can automatically generate a table of contents (also referred to as a toc) from your headings, but this isn’t a feature provided by all Markdown applications. However, if your Markdown application supports heading IDs, you can create a table of contents for your Markdown file using a list and some links.
#### Table of Contents
- [Underline](#underline)
- [Indent](#indent)
- [Center](#center)
- [Color](#color)
渲染输出看起来是这样的：
Table of Contents
Videos
If your Markdown application supports HTML, you should be able to embed a video in your Markdown file by copying and pasting the HTML code provided by a video website like YouTube or Vimeo. If your Markdown application doesn’t support HTML, you can’t embed a video, but you can come close by adding an image and a link to the video. You could do this with practically any video on any video service.
Since YouTube makes this easy, we’ll use them as an example. Take this video, for instance: https://www.youtube.com/watch?v=8q2IjQOzVpE. The last part of the URL (8q2IjQOzVpE) is the ID of the video. We can take that ID and put it in the following template:
[](https://www.youtube.com/watch?v=YOUTUBE-ID)
YouTube automatically generates an image for every video (https://img.youtube.com/vi/YOUTUBE-ID/0.jpg), so we can use that and link the image to the video on YouTube. After we replace the image alt text and add the ID of the video, our example looks like this:
[](https://www.youtube.com/watch?v=PYCxct2e0zI)
渲染输出看起来是这样的：
