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Handlebars.js is an extension to the Mustache templating
created by Chris Wanstrath.
Handlebars.js and Mustache are both logicless templating languages that
keep the view and the code separated like we all know they should be.

Checkout the official Handlebars docs site at


Installing Handlebars is easy. Simply download the package from the official site or the bower repository and add it to your web pages (you should usually use the most recent version).

For web browsers, a free CDN is available at jsDelivr. Advanced usage, such as version aliasing & concocting, is available.

Alternatively, if you prefer having the latest version of handlebars from
the 'master' branch, passing builds of the 'master' branch are automatically
published to S3. You may download the latest passing master build by grabbing
a handlebars-latest.js file from the builds page. When the
build is published, it is also available as a handlebars-gitSHA.js file on
the builds page if you need a version to refer to others.
handlebars-runtime.js builds are also available.

Note: The S3 builds page is provided as a convenience for the community,
but you should not use it for hosting Handlebars in production.


In general, the syntax of Handlebars.js templates is a superset
of Mustache templates. For basic syntax, check out the Mustache

Once you have a template, use the Handlebars.compile method to compile
the template into a function. The generated function takes a context
argument, which will be used to render the template.

var source = "<p>Hello, my name is {{name}}. I am from {{hometown}}. I have " +
             "{{kids.length}} kids:</p>" +
             "<ul>{{#kids}}<li>{{name}} is {{age}}</li>{{/kids}}</ul>";
var template = Handlebars.compile(source);

var data = { "name": "Alan", "hometown": "Somewhere, TX",
             "kids": [{"name": "Jimmy", "age": "12"}, {"name": "Sally", "age": "4"}]};
var result = template(data);

// Would render:
// <p>Hello, my name is Alan. I am from Somewhere, TX. I have 2 kids:</p>
// <ul>
//   <li>Jimmy is 12</li>
//   <li>Sally is 4</li>
// </ul>

Registering Helpers

You can register helpers that Handlebars will use when evaluating your
template. Here's an example, which assumes that your objects have a URL
embedded in them, as well as the text for a link:

Handlebars.registerHelper('link_to', function() {
  return new Handlebars.SafeString("<a href='" + Handlebars.Utils.escapeExpression(this.url) + "'>" + Handlebars.Utils.escapeExpression(this.body) + "</a>");

var context = { posts: [{url: "/hello-world", body: "Hello World!"}] };
var source = "<ul>{{#posts}}<li>{{link_to}}</li>{{/posts}}</ul>"

var template = Handlebars.compile(source);

// Would render:
// <ul>
//   <li><a href='/hello-world'>Hello World!</a></li>
// </ul>

Helpers take precedence over fields defined on the context. To access a field
that is masked by a helper, a path reference may be used. In the example above
a field named link_to on the context object would be referenced using:



By default, the {{expression}} syntax will escape its contents. This
helps to protect you against accidental XSS problems caused by malicious
data passed from the server as JSON.

To explicitly not escape the contents, use the triple-mustache
({{{}}}). You have seen this used in the above example.

Differences Between Handlebars.js and Mustache

Handlebars.js adds a couple of additional features to make writing
templates easier and also changes a tiny detail of how partials work.


Handlebars.js supports an extended expression syntax that we call paths.
Paths are made up of typical expressions and . characters. Expressions
allow you to not only display data from the current context, but to
display data from contexts that are descendants and ancestors of the
current context.

To display data from descendant contexts, use the . character. So, for
example, if your data were structured like:

var data = {"person": { "name": "Alan" }, "company": {"name": "Rad, Inc." } };

You could display the person's name from the top-level context with the
following expression:


You can backtrack using ../. For example, if you've already traversed
into the person object you could still display the company's name with
an expression like {{../}}, so:

{{#with person}}{{name}} - {{../}}{{/with}}

would render:

Alan - Rad, Inc.


When calling a helper, you can pass paths or Strings as parameters. For

Handlebars.registerHelper('link_to', function(title, options) {
  return "<a href='/posts" + this.url + "'>" + title + "!</a>"

var context = { posts: [{url: "/hello-world", body: "Hello World!"}] };
var source = '<ul>{{#posts}}<li>{{{link_to "Post"}}}</li>{{/posts}}</ul>'

var template = Handlebars.compile(source);

// Would render:
// <ul>
//   <li><a href='/posts/hello-world'>Post!</a></li>
// </ul>

When you pass a String as a parameter to a helper, the literal String
gets passed to the helper function.

Block Helpers

Handlebars.js also adds the ability to define block helpers. Block
helpers are functions that can be called from anywhere in the template.
Here's an example:

var source = "<ul>{{#people}}<li>{{#link}}{{name}}{{/link}}</li>{{/people}}</ul>";
Handlebars.registerHelper('link', function(options) {
  return '<a href="/people/' + + '">' + options.fn(this) + '</a>';
var template = Handlebars.compile(source);

var data = { "people": [
    { "name": "Alan", "id": 1 },
    { "name": "Yehuda", "id": 2 }

// Should render:
// <ul>
//   <li><a href="/people/1">Alan</a></li>
//   <li><a href="/people/2">Yehuda</a></li>
// </ul>

Whenever the block helper is called it is given one or more parameters,
any arguments that are passed into the helper in the call, and an options
object containing the fn function which executes the block's child.
The block's current context may be accessed through this.

Block helpers have the same syntax as mustache sections but should not be
confused with one another. Sections are akin to an implicit each or
with statement depending on the input data and helpers are explicit
pieces of code that are free to implement whatever behavior they like.
The mustache spec
defines the exact behavior of sections. In the case of name conflicts,
helpers are given priority.


You can register additional templates as partials, which will be used by
Handlebars when it encounters a partial ({{> partialName}}). Partials
can either be String templates or compiled template functions. Here's an

var source = "<ul>{{#people}}<li>{{> link}}</li>{{/people}}</ul>";

Handlebars.registerPartial('link', '<a href="/people/{{id}}">{{name}}</a>')
var template = Handlebars.compile(source);

var data = { "people": [
    { "name": "Alan", "id": 1 },
    { "name": "Yehuda", "id": 2 }


// Should render:
// <ul>
//   <li><a href="/people/1">Alan</a></li>
//   <li><a href="/people/2">Yehuda</a></li>
// </ul>

Partials can also accept parameters

var source = "<div>{{> roster rosterProperties people=listOfPeople}}</div>";

Handlebars.registerPartial('roster', '<h2>{{rosterName}}</h2>{{#people}}<span>{{id}}: {{name}}</span>{{/people}}')
var template = Handlebars.compile(source);

var data = {
    "listOfPeople": [
        { "name": "Alan", "id": 1 },
        { "name": "Yehuda", "id": 2 }
    "rosterProperties": {
        "rosterName": "Cool People"


// Should render:
// <div>
//  <h2>Cool People</h2>
//   <span>1: Alan</span>
//   <span>2: Yehuda</span>
// </div>


You can add comments to your templates with the following syntax:

{{! This is a comment }}

You can also use real html comments if you want them to end up in the output.

    {{! This comment will not end up in the output }}
    <!-- This comment will show up in the output -->


There are a few Mustache behaviors that Handlebars does not implement.

Precompiling Templates

Handlebars allows templates to be precompiled and included as javascript
code rather than the handlebars template allowing for faster startup time.


The precompiler script may be installed via npm using the npm install -g handlebars


Precompile handlebar templates.
Usage: handlebars template...

  -a, --amd            Create an AMD format function (allows loading with RequireJS)          [boolean]
  -f, --output         Output File                                                            [string]
  -k, --known          Known helpers                                                          [string]
  -o, --knownOnly      Known helpers only                                                     [boolean]
  -m, --min            Minimize output                                                        [boolean]
  -s, --simple         Output template function only.                                         [boolean]
  -r, --root           Template root. Base value that will be stripped from template names.   [string]
  -c, --commonjs       Exports CommonJS style, path to Handlebars module                      [string]
  -h, --handlebarPath  Path to handlebar.js (only valid for amd-style)                        [string]
  -n, --namespace      Template namespace                                                     [string]
  -p, --partial        Compiling a partial template                                           [boolean]
  -d, --data           Include data when compiling                                            [boolean]
  -e, --extension      Template extension.                                                    [string]
  -b, --bom            Removes the BOM (Byte Order Mark) from the beginning of the templates. [boolean]

If using the precompiler's normal mode, the resulting templates will be
stored to the Handlebars.templates object using the relative template
name sans the extension. These templates may be executed in the same
manner as templates.

If using the simple mode the precompiler will generate a single
javascript method. To execute this method it must be passed to
the Handlebars.template method and the resulting object may be used as normal.


Supported Environments

Handlebars has been designed to work in any ECMAScript 3 environment. This includes

Older versions and other runtimes are likely to work but have not been formally
tested. The compiler requires JSON.stringify to be implemented natively or via a polyfill. If using the precompiler this is not necessary.

Selenium Test Status


In a rough performance test, precompiled Handlebars.js templates (in
the original version of Handlebars.js) rendered in about half the
time of Mustache templates. It would be a shame if it were any other
way, since they were precompiled, but the difference in architecture
does have some big performance advantages. Justin Marney, a.k.a.
gotascii, confirmed that with an
independent test. The
rewritten Handlebars (current version) is faster than the old version,
with many performance tests being 5 to 7 times faster than the Mustache equivalent.


See for upgrade notes.

Known Issues

See for known issues and common pitfalls.

Handlebars in the Wild

External Resources

Have a project using Handlebars? Send us a pull request!


Handlebars.js is released under the MIT license.