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Handlebars.js

Handlebars.js is an extension to the Mustache templating
language
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
http://www.handlebarsjs.com and the live demo at http://tryhandlebarsjs.com/.

Installing

See our installation documentation.

Usage

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

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>

Full documentation and more examples are at handlebarsjs.com.

Precompiling Templates

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

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.

Block expressions 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.

Compatibility

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

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

Performance

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.

Upgrading

See release-notes.md for upgrade notes.

Known Issues

See FAQ.md for known issues and common pitfalls.

Handlebars in the Wild

External Resources

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

License

Handlebars.js is released under the MIT license.