Span Elements-CSDN博客

Links

Markdown supports two style of links: inline and reference.

In both styles, the link text is delimited by [square brackets].

To create an inline link, use a set of regular parentheses immediately after the link text’s closing square bracket. Inside the parentheses, put the URL where you want the link to point, along with an optional title for the link, surrounded in quotes. For example:

This is an example inline link.

This link has no title attribute.

Will produce:

This is an example inline link.

This link has no title attribute.

If you’re referring to a local resource on the same server, you can use relative paths:

See my About page for details.

Reference-style links use a second set of square brackets, inside which you place a label of your choosing to identify the link:

This is an example reference-style link.

You can optionally use a space to separate the sets of brackets:

This is [an example] id reference-style link.

Then, anywhere in the document, you define your link label like this, on a line by itself:

That is:

Square brackets containing the link identifier (optionally indented from the left margin using up to three spaces);
followed by a colon;
followed by one or more spaces (or tabs);
followed by the URL for the link;
optionally followed by a title attribute for the link, enclosed in double or single quotes, or enclosed in parentheses.

The following three link definitions are equivalent:

Note: There is a known bug in Markdown.pl 1.0.1 which prevents single quotes from being used to delimit link titles.

The link URL may, optionally, be surrounded by angle brackets:

You can put the title attribute on the next line and use extra spaces or tabs for padding, which tends to look better with longer URLs:

Link definitions are only used for creating links during Markdown processing, and are stripped from your document in the HTML output.

Link definition names may consist of letters, numbers, spaces, and punctuation — but they are not case sensitive. E.g. these two links:

[link text][a]
[link text][A]

are equivalent.

The implicit link name shortcut allows you to omit the name of the link, in which case the link text itself is used as the name. Just use an empty set of square brackets — e.g., to link the word “Google” to the google.com web site, you could simply write:

Google

And then define the link:

Because link names may contain spaces, this shortcut even works for multiple words in the link text:

Visit Daring Fireball for more information.

And then define the link:

Link definitions can be placed anywhere in your Markdown document. I tend to put them immediately after each paragraph in which they’re used, but if you want, you can put them all at the end of your document, sort of like footnotes.

Here’s an example of reference links in action:

I get 10 times more traffic from Google 1 than from
Yahoo 2 or MSN 3.

Using the implicit link name shortcut, you could instead write:

I get 10 times more traffic from Google than from
Yahoo or MSN.

Both of the above examples will produce the following HTML output:

I get 10 times more traffic from Google than from Yahoo or MSN.

For comparison, here is the same paragraph written using Markdown’s inline link style:

I get 10 times more traffic from Google
than from Yahoo or
MSN.

The point of reference-style links is not that they’re easier to write. The point is that with reference-style links, your document source is vastly more readable. Compare the above examples: using reference-style links, the paragraph itself is only 81 characters long; with inline-style links, it’s 176 characters; and as raw HTML, it’s 234 characters. In the raw HTML, there’s more markup than there is text.

With Markdown’s reference-style links, a source document much more closely resembles the final output, as rendered in a browser. By allowing you to move the markup-related metadata out of the paragraph, you can add links without interrupting the narrative flow of your prose.
Emphasis

Markdown treats asterisks (*) and underscores (_) as indicators of emphasis. Text wrapped with one * or _ will be wrapped with an HTML tag; double *’s or _’s will be wrapped with an HTML tag. E.g., this input:

single asterisks

single underscores

double asterisks

double underscores

will produce:

single asterisks

single underscores

double asterisks

double underscores

You can use whichever style you prefer; the lone restriction is that the same character must be used to open and close an emphasis span.

Emphasis can be used in the middle of a word:

unfriggingbelievable