3.2 Includes
3.2.1 引入Jade文件
Includes是代码复用的另一种方式，允许你将一个Jade文件中的内容引入到另一个Jade文件中。
head.jade:
head
title This is head
footer.jade:
footer this is a footer
page.jade:
html
include ./head.jade
body
h1 this is a include demo
include ./footer.jade
page.html:
<html>
<head>
<title>This is head</title>
</head>
<body>
<h1>this is a include demo</h1>
<footer>this is a footer</footer>
</body>
</html>
3.2.2 引入文本文件
除了可以使用includes引入Jade文件，还可以使用它引入文本文件，比如CSS或JavaScript脚本文件。引入样式文件和脚本文件时，文件内容被作为纯文本引入到Jade文件中。
index.jade:
doctype html
html
head
style
include style.css
body
h1 My Site
p Welcome to my super lame site.
script
include script.js
style.css:
h1 { color: red; }
script.js:
console.log('You are awesome');
index.html:
<!doctype html>
<html>
<head>
<style>
h1 { color: red; }
</style>
</head>
<body>
<h1>My Site</h1>
<p>Welcome to my super lame site.</p>
<script>
console.log('You are awesome');
</script>
</body>
</html>
3.2.3 引入过滤器
除了上述两种之外，还可以引入过滤器(过滤器会在3.3节中详细讲解)。
inde.jade
doctype html
html
head
title An Article
body
include:markdown article.md
article.md(markdown文件):
# article.md
This is an article written in markdown.
index.html:
<!doctype html>
<html>
<head>
<title>An Article</title>
</head>
<body>
<h1>article.md</h1>
<p>This is an article written in markdown.</p>
</body>
</html>
在这里引入了一个markdown文件，因为在markdown中#代表h1，所以引入后Jade会自动将其转换为h1标签。