Ever wanted to use the excellent HAML syntax on a javascript project? Me too, so I made one!. This has most of the same functionality as the traditional haml.
Here is the first example(with a little extra added) from the haml site converted to haml-js:
haml-js
!!! XML
!!! strict
%html{ xmlns: "http://www.w3.org/1999/xhtml" }
%head
%title Sample haml template
%body
.profile
.left.column
#date= print_date()
#address= current_user.address
.right.column
#email= current_user.email
#bio= current_user.bio
html
<?xml version='1.0' encoding='utf-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head><title>Sample haml template
</title></head><body><div class="profile"><div class="left column"><div id="date">January 1, 2009
</div><div id="address">Richardson, TX
</div></div><div class="right column"><div id="email">[email protected]
</div><div id="bio">Experienced software professional...
</div></div></div></body></html>
Note that this works almost the same as ruby's haml, but doesn't pretty print the html. This would greatly slow down and complicate the code. If you really want pretty printed html, then I suggest writing one using the xml parser library and process the resulting html..
This is the new (as of 0.2.0) way to generate haml templates. A haml template is a live function that takes in "this" context and a "locals" variable. This compile step takes a few milliseconds to complete so it should be done at startup and the resulting function should be cached. Then to use the template function you simply call it with the desired local variables and it will output html at blazing speeds (we're talking millions per second on my 13" MBP)
Compile and store a template:
var main = Haml(main_haml);
Then use it whenever you need a new version:
main({name: "Tim", age: 28});
That's it. Haml templating made easy!
If you want to store the generated javascript to a file to skip the compile step later on you can either decompile the template function or use the compile and optimize advanced functions directly.
Given a haml template as raw text, this compiles it to a javascript expression that can later be eval'ed to get the final HTML.
The following input:
#home
= title
%ul.menu
%li Go Home
%li Go Back
Produces the following JavaScript expression:
"<div id=\"home\">" +
title +
"\n" +
"<ul class=\"menu\">" +
"<li>" +
"Go Home\n" +
"</li>" +
"<li>" +
"Go Back\n" +
"</li>" +
"</ul>" +
"</div>"
Takes the output of compile and optimizes it to run faster with the tradeoff of longer compile time. This is useful for framework developers wanting to use haml in their framework and want to cache the compiled templates for performance.
With the previous input it outputs:
"<div id=\"home\">" +
title +
"\n<ul class=\"menu\"><li>Go Home\n</li><li>Go Back\n</li></ul></div>"
Notice how congruent static strings are merged into a single string literal when possible.
Context is the value of this in the template, and locals is a hash of local variables.
This is a convenience function that compiles and executes to html in one shot. Most casual users will want to use this function exclusively.
The text parameter is the haml source already read from a file.
The three recognized options are:
- context: This is the
thiscontext within the haml template. - locals: This is an object that's used in the
withscope. Basically it creates local variables and function accessible to the haml template. - optimize: This is a flag to tell the compiler to use the extra optimizations.
See test.js for an example usage of Haml.render
New in version 0.2.0 there is string interpolation throughout. This means that the body of regular text areas can have embedded code. This is true for attributes and the contents of plugins like javascript and markdown also. If you notice an area that doesn't support interpolation and it should then send me a note and I'll add it.
There are plugins in the parser for things like inline script tags, css blocks, and support for if statements and for loops.
if statements evaluate a condition for truthiness (as opposed to a strict comparison to true) and includes the content inside the block if it's truthy.
:if todolist.length > 20
%p Oh my, you are a busy fellow!
:each loops allow you to loop over a collection including a block of content once for each item. You need to what variable to pull the data from and where to put the index and value. The index variable is optional and defaults to __key__.
Here is an example over a simple array.
%ul.todolist
:each item in todolist
%li= item.description
You can loop over the keys and values of objects too (Note the inner :each loop)
:each item in data
:if item.age < 100
%dl
:each name, value in item
%dt&= name
%dd&= value
It's easy to embed javascript and css blocks in an haml document.
%head
:javascript
function greet(message) {
alert("Message from MCP: " + message);
}
%title Script and Css test
:css
body {
color: pink;
}
%body{ onload: "greet(\"I'm Pink\")" } COLOR ME PINK
This compiles to the following HTML:
<head>
<script type="text/javascript">
//<![CDATA[
function greet(message) {
alert("Message from MCP: " + message);
}
//]]>
</script>
<title>Script and Css test
</title>
<style type="text/css">
body {
color: pink;
}
</style>
</head><body onload="greet("I'm Pink")"> COLOR ME PINK
</body>
If you want to use this project and something is missing then send me a message. I'm very busy and have several open source projects I manage. I'll contribute to this project as I have time, but if there is more interest for some particular aspect, I'll work on it a lot faster. Also you're welcome to fork this project and send me patches/pull-requests.
The haml compiler isn't built for speed, it's built for maintainability. The actual generated templates, however are blazing fast. I benchmarked them with over 65 million renders per second on a small (20 line) template with some dynamic data on my laptop. Compare this to the 629 compiles per second I got out of the compiler. The idea is that you pre-compile your templates and reuse them on every request. While 629 per second is nothing compared to 65 million, that still means that your server with over 600 different views can boot up in about a second. I think that's fine for something that only happens every few weeks.
Haml-js is licensed under the MIT license.