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Blade - HTML Template Compiler

Blade is a HTML Template Compiler, inspired by Jade & Haml, implemented in JavaScript, so it will run on your microwave oven.

Never write HTML again. Please.

Table of Contents


  • Write extremely readable short-hand HTML
  • Insert escaped and unescaped text and vanilla JavaScript code
  • Code and text are escaped by default for security/convenience
  • Functions (like Jade mixins)
  • Dynamic file includes
  • Regular blocks and Parameterized blocks
  • True client-side template support with caching, etc.
  • Supports Express.JS
  • HTML Comments and block comments
  • Text filters

Blade does more than Jade, and it does less than Jade. Your Jade templates will probably need some modifications before they will work with Blade.


Most of Blade was implemented in less than 4 days. So, there is still stuff to do:

  • Better error handling and error reporting
  • Finish client-side runtime
  • Better test suite
  • Change tag ending based on doctype
  • Executable to compile and/or render templates via command line
  • Text string interpolation
  • More text filters?


for Node (via npm): npm install blade

for Browsers:

Runtime only: wget

Compiler + Runtime: wget



Like Jade, a tag is simply a word. For example, the string html will render to <html></html>.

You can have 'id's:


which renders as <div id="awesome"></div>.

Any number of classes work, separated by a dot (.)


which renders as <div class="task-details container"></div>.

Tag attributes? Yep, they work pretty much like Jade, too. Put attributes in parenthesis, separate attributes with a comma, space, newline, or whatever.

a(href="/homepage", onclick="return false;") renders as:

<a href="/homepage" onclick="return false;"></a>

You can also have line feeds or weird whitespace between attributes, just like in Jade. Whatever. This works, for example:

        value="Your email here"

Yes... the class attribute is handled with extra special care. Pass an array or string. Yes, classes (delimited by ".") from before will be merged with the value of the attribute."another dude") renders as: <div id="foo" class="bar dummy another dude"></div>

div div div is annoying... so we can omit this if we specify an id or some classes:


renders as:

<div id="foo"></div><div class="bar"></div><div id="this" class="is cool"></div>

Also, tags without matching ending tags like <img> render properly.


It works. You can indent with any number of spaces or with a single tab character. Jade gives you a lot of weird indent flexibility. Blade, by design, does not.


renders as:

<html><head></head><body><div id="content"></div></body></html>


It works, too. Simply place content after the tag like this:

p This text is "escaped" by default. Kinda neat.

renders as:

<p>This text is &quot;escaped&quot; by default. Kinda neat.</p>

Want unescaped text? Large blocks of text? Done.

p! This will be <strong>unescaped</strong> text.
        How about a block? (this is "escaped", btw)
        Yep. It just works!

renders as:

<p>This will be <strong>unescaped</strong> text.
How about a block? (this is &quot;escaped&quot;, btw)
Yep. It just works!

Rules are:

  • Text is escaped by default
  • Want unescaped text? Precede with a !
  • Large text block? Use | and indent properly.
  • Unescaped text block? Use |! or even just ! works.

Text filters

Need <br/> tags inserted? Use a built-in filter, perhaps?

        How about some text with some breaks?

        Yep! It works!

renders as:

<p>How about some text with some breaks?<br/><br/>Yep! It works!</p>

Built-in text filters include:

  • :nl2br - Converts newline characters to <br/>
  • :cdata - Surrounds text like this: <![CDATA[ ...text goes here... ]]> Text should not contain ]]>.
  • :markdown (must have markdown-js installed)
  • :md (alias for :markdown)

Filters are essentially functions that accept a text string and return HTML. They cannot modify the AST directly.

And, you can add custom filters at runtime using the API.


Use dash (-) to specify a code block. Use equals (=) to specify code output. A few examples, please?

Code blocks:

    - if(task.completed)
        p You are done. Do more! >:O
    - else
        p Get to work, slave!

Code that outputs (i.e. in a text block or at the end of a tag). It's just like a text block, except with an =.

#taskStatus= task.completed ? "Yay!" : "Awww... it's ok."
    | The task was due on
    = task.dueDate

When using code that outputs, the default is to escape all text. To turn off escaping, just prepend a "!", as before:

    != some_html

Extra "|" characters are okay, too. Just don't forget that stuff after the "=" means JavaScript code!

    |= "escape me away & away"

renders <p>escape me away &amp; away</p>

Variable names to avoid

Blade, like other template engines, defines local variables within every single view. You should avoid using these names in your view templates whenever possible:

  • locals
  • runtime
  • cb
  • buf
  • __ (that's two underscores)
  • Any of the compiler options (i.e. debug, minify, etc.)
  • blade


Don't forget a doctype! Actually, you can, whatever... defaults to HTML 5, of course.

Add a doctype using the doctype keyword or !!! like this:

!!! 5 means use HTML 5 doctype.

Use the list of built-in doctypes or pass your own like this:

doctype html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN

which renders as <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN>

Put the doctype at the top of your Blade files, please. Here is the list of built-in doctypes:

var doctypes = exports.doctypes = {
  '5': '<!DOCTYPE html>',
  'xml': '<?xml version="1.0" encoding="utf-8" ?>',
  'default': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">',
  'transitional': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">',
  'strict': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "">',
  'frameset': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "">',
  '1.1': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "">',
  'basic': '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "">',
  'mobile': '<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN" "">'

Yes, you can modify the list of built-in doctypes through the API. Why would you, though?


Use // for a line comment. Use //- if you don't want the comment to be rendered. Block comments work, too.

//Comment example 1
//-Comment example 2
    p Block comments work, too

renders as:

<!--Comment example 1--><!--<div id="wow"></div><p>Block comments work, too</p>-->

Conditional comments work like this:

    //if lt IE 8

renders as:

<head><!--[if lt IE 8]><script src="/ie-really-sux.js"></script><![endif]--></head>


Functions are reusable mini-templates. They are similar to 'mixins' in Jade.

Defining a function:

function textbox(name, value)
    input(type="text", name=name, value=value)

Calling a function and inserting into template structure:

    !=functions.textbox("firstName", "Blake")

Or... maybe just putting the generated HTML into a variable?

- var text = functions.textbox("firstName", "Blake");

Both examples would render:

<form><input type="text" name="firstName" value="Blake"/></form>

Limitation: Don't use a local variable with the name functions... for obvious reasons.

Dynamic file includes

include "file.blade"

This will dynamically (at runtime) insert "file.blade" right into the current view, as if it was a single file


Blocks allow you to mark places in your template with code that may or may not be rendered later.

You can do a lot with blocks, including template inheritance, etc. They behave quite differently from Jade.

There are two types of blocks: regular blocks and parameterized blocks.

Regular blocks

Regular blocks are defined using the "block" keyword followed by a block name. Then, you optionally put indented block content below. Like this:

block regular_block
    h1 Hello
    p This is a test

Assuming nothing else happens to the block, it will be rendered as <h1>Hello</h1><p>This is a test</p> as expected. Empty blocks are also permitted. A simple, empty block looks like this: block block_name

Of course, the purpose of declaring/defining a block is to possibly modify it later. You can modify a block using three different commands:

  • Use the append keyword to append to the matching block.
  • Use the prepend keyword to prepend to the matching block.
  • Use the replace keyword to replace the matching block.


append regular_block
    p This is also a test

Replacing a block

Replacing a block is somewhat confusing, so I will explain further. If you replace a block, you are not changing the location of the defined block; you are only replacing the content of the block at its pre-defined location. If you want to change the location of a block, simply re-define a new block (see below).

In addition, when you replace a block, all previously appended and prepended content is lost. The behavior is usually desired, but it can sometimes be a source of confusion.

If you replace a parameterized block (described below), you cannot call "render" on that block anymore.

At this time, you cannot replace a block with a parameterized block. The "replace" command will not accept parameters.

Parameterized blocks

The other type of block is called a parameterized block, and it looks like this:

block regular_block(headerText, text)
    h1= headerText
    p= text

Parameterized blocks do not render automatically because they require parameters. Therefore, assuming nothing else happens to the block, the block will not be rendered at all.

To render a block, use the "render" keyword like this:

render regular_block("Some header text", 'Some "paragraph" text')

Now, assuming nothing else happens to the block, the block will be rendered as:

<h1>Some header text</h1><p>Some &quot;paragraph&quot; text</p>

Parameterized blocks are really cool because "append", "prepend", and "replace" all work, too. You don't need to "render" the block to use "append", "prepend", and "replace".

Another example:

    block header(pageTitle)
        title= pageTitle
    h1 Hello
    render header("Page Title")
    append header
    prepend header

Will output:

    <title>Page Title</title>
    <script src="text/javascript"></script>

What happens if I define the same block more than once?

You can re-define a block that has already been defined with another "block" statement. This completely destroys the previously defined block. Previously executed "append", "prepend", "replace", and "render" blocks do not affect the re-defined block.

In summary...

  • Use the block keyword to mark where the block will go (block definition).
  • Use the render keyword to render the matching "parameterized" block. Do not use this on a regular block.
  • Use the append keyword to append to the matching block.
  • Use the prepend keyword to prepend to the matching block.
  • Use the replace keyword to replace the matching block.

You may render, append to, prepend to, and replace undefined blocks; however, this, of course, has no effect. No error messages occur if you do this because a compiled view can also be included, and the parent view may have the block defined.

Template Inheritance

There is no extends keyword. Just use blocks and includes:


        block title(pageTitle)
        block body


include "layout.blade"
render title("Homepage")
replace block body
    h1 Hello, World

If you render layout.blade, you get: <html><head></head><body></body></html>, but if you render homepage.blade, you get:

        <h1>Hello, World</h1>


var blade = require('blade');

blade.compile(string, [options,] cb)

Asynchronously compiles a Blade template from a string.

  • string is a string of Blade
  • options include:
    • filename - the filename being compiled (required when using includes or the cache option)
    • cache - if true, the compiled template will be cached
    • debug - outputs debug info to the console (defaults to false)
    • minify - if true, Blade generates a minified template without debugging information (defaults to false)
    • includeSource - if true, Blade inserts the Blade source file directly into the compiled template, which can further improve error reporting, although the size of the template is increased significantly. (defaults to false)
    • doctypes - use this Object instead of blade.Compiler.doctypes
    • inlineTags - use this Object instead of blade.Compiler.inlineTags
    • filters - use this Object instead of blade.Compiler.filters
  • cb is a function of the form: cb(err, fn) where err contains any parse or compile errors and fn is the compiled template. If an error occurs, err may contain the following properties:
    • message - The error message
    • expected - If the error is a 'SyntaxError', this is an array of expected tokens
    • found - If the error is a 'SyntaxError', this is the token that was found
    • filename - The filename where the error occurred
    • offset - The offset in the string where the error occurred
    • line - The line # where the error occurred
    • column - The column # where the error occurred

Note: if there is a problem with the Blade compiler, or more likely, if there is a syntax error with the JavaScript code in your template, Node.js will not provide any line number or other information about the error. At the time of this writing, this is a limitation of the Google V8 engine.

You can render a compiled template by calling the function: tmpl(locals, cb) - locals are the local variables to be passed to the view template - cb is a function of the form function(err, html) where err contains any runtime errors and html contains the rendered HTML.

In addition, a compiled template has these properties: - template - a function that also renders the template but accepts 3 parameters: tmpl.template(locals, runtime, cb). This simply allows you to use a custom runtime environment, if you choose to do so.

You can call tmpl.toString(), just like you can on any other JavaScript function. This might be useful for client-side templates, for example.

blade.compileFile(filename, [options,] cb)

Asynchronously compile a Blade template from a filename on the filesystem.

  • filename is the filename
  • options - same as blade.compile above, except filename option is always overwritten with the filename specified.
  • cb - same as blade.compile above

blade.renderFile(filename, options, cb)

Convenience function to asynchronously compile a template and render it.

  • filename is the filename
  • options - same as blade.compileFile above. This object is also passed directly to the view, so it should also contain your view's local variables.
  • cb - a function of the form function(err, html)


The compiler itself. It has some useful methods and properties.


Just generates the parse tree for the string. For debugging purposes only.

var blade = require('blade');
blade.compile("string of blade", options, function(err, tmpl) {
    tmpl(locals, function(err, html) {

Implementation Details

The Blade parser is built using PEG.js. Thanks to the PEG.js team for making this project much easier than I had anticipated!


See the LICENSE.txt file.

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