jade-language.md 20KB
Syntax
Tags
A tag is simply a leading word:
html
for example is converted to <html></html>
tags can also have ids:
div#container
which would render <div id="container"></div>
how about some classes?
div.user-details
renders <div class="user-details"></div>
multiple classes? and an id? sure:
div#foo.bar.baz
renders <div id="foo" class="bar baz"></div>
div div div sure is annoying, how about:
#foo
.bar
which is syntactic sugar for what we have already been doing, and outputs:
<div id="foo"></div><div class="bar"></div>
Tag Text
Simply place some content after the tag:
p wahoo!
renders <p>wahoo!</p>.
well cool, but how about large bodies of text:
p
| foo bar baz
| rawr rawr
| super cool
| go jade go
renders <p>foo bar baz rawr.....</p>
interpolation? yup! both types of text can utilize interpolation,
if we passed { name: 'tj', email: 'tj@vision-media.ca' } to the compiled function we can do the following:
#user #{name} <#{email}>
outputs <div id="user">tj <tj@vision-media.ca></div>
Actually want #{} for some reason? escape it!
p \#{something}
now we have <p>#{something}</p>
We can also utilize the unescaped variant !{html}, so the following
will result in a literal script tag:
- var html = "<script></script>"
| !{html}
Nested tags that also contain text can optionally use a text block:
label
| Username:
input(name='user[name]')
or immediate tag text:
label Username:
input(name='user[name]')
As an alternative, we may use a trailing . to indicate a text block, for example:
p.
foo asdf
asdf
asdfasdfaf
asdf
asd.
outputs:
<p>foo asdf
asdf
asdfasdfaf
asdf
asd.
</p>
This however differs from a trailing . followed by a space, which although is ignored by the Jade parser, tells Jade that this period is a literal:
p .
outputs:
<p>.</p>
It should be noted that text blocks should be doubled escaped. For example if you desire the following output.
<p>foo\bar</p>
use:
p.
foo\\bar
Comments
Single line comments currently look the same as JavaScript comments,
aka // and must be placed on their own line:
// just some paragraphs
p foo
p bar
would output
<!-- just some paragraphs -->
<p>foo</p>
<p>bar</p>
Jade also supports unbuffered comments, by simply adding a hyphen:
//- will not output within markup
p foo
p bar
outputting
<p>foo</p>
<p>bar</p>
Block Comments
A block comment is legal as well:
body
//
#content
h1 Example
outputting
<body>
<!--
<div id="content">
<h1>Example</h1>
</div>
-->
</body>
Jade supports conditional-comments as well, for example:
head
//if lt IE 8
script(src='/ie-sucks.js')
outputs:
<head>
<!--[if lt IE 8]>
<script src="/ie-sucks.js"></script>
<![endif]-->
</head>
Nesting
Jade supports nesting to define the tags in a natural way:
ul
li.first
a(href='#') foo
li
a(href='#') bar
li.last
a(href='#') baz
Block Expansion
Block expansion allows you to create terse single-line nested tags, the following example is equivalent to the nesting example above.
ul
li.first: a(href='#') foo
li: a(href='#') bar
li.last: a(href='#') baz
Case
The case statement takes the following form:
html
body
friends = 10
case friends
when 0
p you have no friends
when 1
p you have a friend
default
p you have #{friends} friends
Block expansion may also be used:
friends = 5
html
body
case friends
when 0: p you have no friends
when 1: p you have a friend
default: p you have #{friends} friends
Attributes
Jade currently supports ( and ) as attribute delimiters.
a(href='/login', title='View login page') Login
When a value is undefined or null the attribute is not added,
so this is fine, it will not compile something="null".
div(something=null)
Boolean attributes are also supported:
input(type="checkbox", checked)
Boolean attributes with code will only output the attribute when true:
input(type="checkbox", checked=someValue)
Multiple lines work too:
input(type='checkbox',
name='agreement',
checked)
Multiple lines without the comma work fine:
input(type='checkbox'
name='agreement'
checked)
Funky whitespace? fine:
input(
type='checkbox'
name='agreement'
checked)
Colons work:
rss(xmlns:atom="atom")
Suppose we have the user local { id: 12, name: 'tobi' }
and we wish to create an anchor tag with href pointing to “/user/12”
we could use regular javascript concatenation:
a(href='/user/' + user.id)= user.name
or we could use jade’s interpolation, which I added because everyone using Ruby or CoffeeScript seems to think this is legal js..:
a(href='/user/#{user.id}')= user.name
The class attribute is special-cased when an array is given,
allowing you to pass an array such as bodyClasses = ['user', 'authenticated'] directly:
body(class=bodyClasses)
HTML
Inline html is fine, we can use the pipe syntax to write arbitrary text, in this case some html:
html
body
| <h1>Title</h1>
| <p>foo bar baz</p>
Or we can use the trailing . to indicate to Jade that we
only want text in this block, allowing us to omit the pipes:
html
body.
<h1>Title</h1>
<p>foo bar baz</p>
Both of these examples yield the same result:
<html><body><h1>Title</h1>
<p>foo bar baz</p>
</body></html>
The same rule applies for anywhere you can have text in jade, raw html is fine:
html
body
h1 User <em>#{name}</em>
Doctypes
To add a doctype simply use !!!, or doctype followed by an optional value:
!!!
or
doctype
Will output the html 5 doctype, however:
!!! transitional
Will output the transitional doctype.
Doctypes are case-insensitive, so the following are equivalent:
doctype Basic
doctype basic
it’s also possible to simply pass a doctype literal:
doctype html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN"
yielding:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN">
Below are the doctypes defined by default, which can easily be extended:
var doctypes = exports.doctypes = {
'5': '<!DOCTYPE html>',
'default': '<!DOCTYPE html>',
'xml': '<?xml version="1.0" encoding="utf-8" ?>',
'transitional': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">',
'strict': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">',
'frameset': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">',
'1.1': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">',
'basic': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd">',
'mobile': '<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN" "http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">'
};
To alter the default simply change:
jade.doctypes.default = 'whatever you want';
Filters
Filters are prefixed with :, for example :markdown and
pass the following block of text to an arbitrary function for processing. View the features
at the top of this document for available filters.
body
:markdown
Woah! jade _and_ markdown, very **cool**
we can even link to [stuff](http://google.com)
Renders:
<body><p>Woah! jade <em>and</em> markdown, very <strong>cool</strong> we can even link to <a href="http://google.com">stuff</a></p></body>
Code
Jade currently supports three classifications of executable code. The first
is prefixed by -, and is not buffered:
- var foo = 'bar';
This can be used for conditionals, or iteration:
- for (var key in obj)
p= obj[key]
Due to Jade’s buffering techniques the following is valid as well:
- if (foo)
ul
li yay
li foo
li worked
- else
p oh no! didnt work
Hell, even verbose iteration:
- if (items.length)
ul
- items.forEach(function(item){
li= item
- })
Anything you want!
Next up we have escaped buffered code, which is used to
buffer a return value, which is prefixed by =:
- var foo = 'bar'
= foo
h1= foo
Which outputs bar<h1>bar</h1>. Code buffered by = is escaped
by default for security, however to output unescaped return values
you may use !=:
p!= aVarContainingMoreHTML
Jade also has designer-friendly variants, making the literal JavaScript more expressive and declarative. For example the following assignments are equivalent, and the expression is still regular javascript:
- var foo = 'foo ' + 'bar'
foo = 'foo ' + 'bar'
Likewise Jade has first-class if, else if, else, until, while, unless among others, however you must remember that the expressions are still regular javascript:
if foo == 'bar'
ul
li yay
li foo
li worked
else
p oh no! didnt work
Iteration
Along with vanilla JavaScript Jade also supports a subset of
constructs that allow you to create more designer-friendly templates,
one of these constructs is each, taking the form:
each VAL[, KEY] in OBJ
An example iterating over an array:
- var items = ["one", "two", "three"]
each item in items
li= item
outputs:
<li>one</li>
<li>two</li>
<li>three</li>
iterating an array with index:
items = ["one", "two", "three"]
each item, i in items
li #{item}: #{i}
outputs:
<li>one: 0</li>
<li>two: 1</li>
<li>three: 2</li>
iterating an object’s keys and values:
obj = { foo: 'bar' }
each val, key in obj
li #{key}: #{val}
would output <li>foo: bar</li>
Internally Jade converts these statements to regular
JavaScript loops such as users.forEach(function(user){,
so lexical scope and nesting applies as it would with regular
JavaScript:
each user in users
each role in user.roles
li= role
You may also use for if you prefer:
for user in users
for role in user.roles
li= role
Conditionals
Jade conditionals are equivalent to those using the code (-) prefix,
however allow you to ditch parenthesis to become more designer friendly,
however keep in mind the expression given is regular JavaScript:
for user in users
if user.role == 'admin'
p #{user.name} is an admin
else
p= user.name
is equivalent to the following using vanilla JavaScript literals:
for user in users
- if (user.role == 'admin')
p #{user.name} is an admin
- else
p= user.name
Jade also provides unless which is equivalent to if (!(expr)):
for user in users
unless user.isAnonymous
p
| Click to view
a(href='/users/' + user.id)= user.name
Template inheritance
Jade supports template inheritance via the block and extends keywords. A block is simply a “block” of Jade that may be replaced within a child template, this process is recursive. To activate template inheritance in Express 2.x you must add: app.set('view options', { layout: false });.
Jade blocks can provide default content if desired, however optional as shown below by block scripts, block content, and block foot.
html
head
title My Site - #{title}
block scripts
script(src='/jquery.js')
body
block content
block foot
#footer
p some footer content
Now to extend the layout, simply create a new file and use the extends directive as shown below, giving the path (with or without the .jade extension). You may now define one or more blocks that will override the parent block content, note that here the foot block is not redefined and will output “some footer content”.
extends layout
block scripts
script(src='/jquery.js')
script(src='/pets.js')
block content
h1= title
each pet in pets
include pet
It’s also possible to override a block to provide additional blocks, as shown in the following example where content now exposes a sidebar and primary block for overriding, or the child template could override content all together.
extends regular-layout
block content
.sidebar
block sidebar
p nothing
.primary
block primary
p nothing
Block append / prepend
Jade allows you to replace (default), prepend, or append blocks. Suppose for example you have default scripts in a “head” block that you wish to utilize on every page, you might do this:
html
head
block head
script(src='/vendor/jquery.js')
script(src='/vendor/caustic.js')
body
block content
Now suppose you have a page of your application for a JavaScript game, you want some game related scripts as well as these defaults, you can simply append the block:
extends layout
block append head
script(src='/vendor/three.js')
script(src='/game.js')
When using block append or block prepend the block is optional:
extends layout
append head
script(src='/vendor/three.js')
script(src='/game.js')
Includes
Includes allow you to statically include chunks of Jade, or other content like css, or html which lives in separate files. The classical example is including a header and footer. Suppose we have the following directory structure:
./layout.jade
./includes/
./head.jade
./foot.jade
and the following layout.jade:
html
include includes/head
body
h1 My Site
p Welcome to my super amazing site.
include includes/foot
both includes includes/head and includes/foot are
read relative to the filename option given to layout.jade,
which should be an absolute path to this file, however Express
does this for you. Include then parses these files, and injects
the AST produced to render what you would expect:
<html>
<head>
<title>My Site</title>
<script src="/javascripts/jquery.js">
</script><script src="/javascripts/app.js"></script>
</head>
<body>
<h1>My Site</h1>
<p>Welcome to my super lame site.</p>
<div id="footer">
<p>Copyright>(c) foobar</p>
</div>
</body>
</html>
As mentioned include can be used to include other content
such as html or css. By providing an explicit filter name
with include:, Jade will read that file in, apply the
filter, and insert that content into the output.
html
head
//- css and js have simple filters that wrap them in
<style> and <script> tags, respectively
include stylesheet.css
include script.js
body
//- use the "markdown" filter to convert Markdown to HTML
include:markdown introduction.markdown
//- html files have no filter and are included verbatim
include content.html
Include directives may also accept a block, in which case the
the given block will be appended to the last block defined
in the file. For example if head.jade contains:
head
script(src='/jquery.js')
We may append values by providing a block to include head
as shown below, adding the two scripts.
html
include head
script(src='/foo.js')
script(src='/bar.js')
body
h1 test
You may also yield within an included template, allowing you to explicitly mark where the block given to include will be placed. Suppose for example you wish to prepend scripts rather than append, you might do the following:
head
yield
script(src='/jquery.js')
script(src='/jquery.ui.js')
Since included Jade is parsed and literally merges the AST, lexically scoped variables function as if the included Jade was written right in the same file. This means include may be used as sort of partial, for example suppose we have user.jade which utilizes a user variable.
h1= user.name
p= user.occupation
We could then simply include user while iterating users, and since the user variable is already defined within the loop the included template will have access to it.
users = [{ name: 'Tobi', occupation: 'Ferret' }]
each user in users
.user
include user
yielding:
<div class="user">
<h1>Tobi</h1>
<p>Ferret</p>
</div>
If we wanted to expose a different variable name as user since user.jade references that name, we could simply define a new variable as shown here with user = person:
each person in users
.user
user = person
include user
Mixins
Mixins are converted to regular JavaScript functions in the compiled template that Jade constructs. Mixins may take arguments, though not required:
mixin list
ul
li foo
li bar
li baz
Utilizing a mixin without args looks similar, just without a block:
h2 Groceries
mixin list
Mixins may take one or more arguments as well, the arguments are regular javascripts expressions, so for example the following:
mixin pets(pets)
ul.pets
- each pet in pets
li= pet
mixin profile(user)
.user
h2= user.name
mixin pets(user.pets)
Would yield something similar to the following html:
<div class="user">
<h2>tj</h2>
<ul class="pets">
<li>tobi</li>
<li>loki</li>
<li>jane</li>
<li>manny</li>
</ul>
</div>
Generated Output
Suppose we have the following Jade:
- var title = 'yay'
h1.title #{title}
p Just an example
When the compileDebug option is not explicitly false, Jade
will compile the function instrumented with __.lineno = n;, which
in the event of an exception is passed to rethrow() which constructs
a useful message relative to the initial Jade input.
function anonymous(locals) {
var __ = { lineno: 1, input: "- var title = 'yay'\nh1.title #{title}\np Just an example", filename: "testing/test.js" };
var rethrow = jade.rethrow;
try {
var attrs = jade.attrs, escape = jade.escape;
var buf = [];
with (locals || {}) {
var interp;
__.lineno = 1;
var title = 'yay'
__.lineno = 2;
buf.push('<h1');
buf.push(attrs({ "class": ('title') }));
buf.push('>');
buf.push('' + escape((interp = title) == null ? '' : interp) + '');
buf.push('</h1>');
__.lineno = 3;
buf.push('<p>');
buf.push('Just an example');
buf.push('</p>');
}
return buf.join("");
} catch (err) {
rethrow(err, __.input, __.filename, __.lineno);
}
}
When the compileDebug option is explicitly false, this instrumentation
is stripped, which is very helpful for light-weight client-side templates. Combining Jade’s options with the ./runtime.js file in this repo allows you
to toString() compiled templates and avoid running the entire Jade library on
the client, increasing performance, and decreasing the amount of JavaScript
required.
function anonymous(locals) {
var attrs = jade.attrs, escape = jade.escape;
var buf = [];
with (locals || {}) {
var interp;
var title = 'yay'
buf.push('<h1');
buf.push(attrs({ "class": ('title') }));
buf.push('>');
buf.push('' + escape((interp = title) == null ? '' : interp) + '');
buf.push('</h1>');
buf.push('<p>');
buf.push('Just an example');
buf.push('</p>');
}
return buf.join("");
}