| [](https://travis-ci.org/wycats/handlebars.js) |
| [](https://ci.appveyor.com/project/wycats/handlebars-js) |
| [](https://saucelabs.com/u/handlebars) |
| |
| Handlebars.js |
| ============= |
| |
| Handlebars.js is an extension to the [Mustache templating |
| language](http://mustache.github.com/) 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](http://www.handlebarsjs.com) and the live demo at [http://tryhandlebarsjs.com/](http://tryhandlebarsjs.com/). |
| |
| Installing |
| ---------- |
| |
| See our [installation documentation](http://handlebarsjs.com/installation.html). |
| |
| Usage |
| ----- |
| In general, the syntax of Handlebars.js templates is a superset |
| of Mustache templates. For basic syntax, check out the [Mustache |
| manpage](http://mustache.github.com/mustache.5.html). |
| |
| 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. |
| |
| ```js |
| 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](http://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](http://handlebarsjs.com/precompilation.html). |
| |
| 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. |
| |
| - [Nested Paths](http://handlebarsjs.com/#paths) |
| - [Helpers](http://handlebarsjs.com/#helpers) |
| - [Block Expressions](http://handlebarsjs.com/#block-expressions) |
| - [Literal Values](http://handlebarsjs.com/#literals) |
| - [Delimited Comments](http://handlebarsjs.com/#comments) |
| |
| 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](http://mustache.github.io/mustache.5.html) 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. |
| - Handlebars deviates from Mustache slightly in that it does not perform recursive lookup by default. The compile time `compat` flag must be set to enable this functionality. Users should note that there is a performance cost for enabling this flag. The exact cost varies by template, but it's recommended that performance sensitive operations should avoid this mode and instead opt for explicit path references. |
| - The optional Mustache-style lambdas are not supported. Instead Handlebars provides its own lambda resolution that follows the behaviors of helpers. |
| - Alternative delimiters are not supported. |
| |
| |
| Supported Environments |
| ---------------------- |
| |
| Handlebars has been designed to work in any ECMAScript 3 environment. This includes |
| |
| - Node.js |
| - Chrome |
| - Firefox |
| - Safari 5+ |
| - Opera 11+ |
| - IE 6+ |
| |
| 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. |
| |
| [](https://saucelabs.com/u/handlebars) |
| |
| 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](http://github.com/gotascii), confirmed that with an |
| [independent test](http://sorescode.com/2010/09/12/benchmarks.html). The |
| rewritten Handlebars (current version) is faster than the old version, |
| with many [performance tests](https://travis-ci.org/wycats/handlebars.js/builds/33392182#L538) being 5 to 7 times faster than the Mustache equivalent. |
| |
| |
| Upgrading |
| --------- |
| |
| See [release-notes.md](https://github.com/wycats/handlebars.js/blob/master/release-notes.md) for upgrade notes. |
| |
| Known Issues |
| ------------ |
| |
| See [FAQ.md](https://github.com/wycats/handlebars.js/blob/master/FAQ.md) for known issues and common pitfalls. |
| |
| |
| Handlebars in the Wild |
| ---------------------- |
| |
| * [Assemble](http://assemble.io), by [@jonschlinkert](https://github.com/jonschlinkert) |
| and [@doowb](https://github.com/doowb), is a static site generator that uses Handlebars.js |
| as its template engine. |
| * [Cory](https://github.com/leo/cory), by [@leo](https://github.com/leo), is another tiny static site generator |
| * [CoSchedule](http://coschedule.com) An editorial calendar for WordPress that uses Handlebars.js |
| * [dashbars](https://github.com/pismute/dashbars) A modern helper library for Handlebars.js. |
| * [Ember.js](http://www.emberjs.com) makes Handlebars.js the primary way to |
| structure your views, also with automatic data binding support. |
| * [Ghost](https://ghost.org/) Just a blogging platform. |
| * [handlebars_assets](http://github.com/leshill/handlebars_assets): A Rails Asset Pipeline gem |
| from Les Hill (@leshill). |
| * [handlebars-helpers](https://github.com/assemble/handlebars-helpers) is an extensive library |
| with 100+ handlebars helpers. |
| * [handlebars-layouts](https://github.com/shannonmoeller/handlebars-layouts) is a set of helpers which implement extendible and embeddable layout blocks as seen in other popular templating languages. |
| * [hbs](http://github.com/donpark/hbs): An Express.js view engine adapter for Handlebars.js, |
| from Don Park. |
| * [koa-hbs](https://github.com/jwilm/koa-hbs): [koa](https://github.com/koajs/koa) generator based |
| renderer for Handlebars.js. |
| * [jblotus](http://github.com/jblotus) created [http://tryhandlebarsjs.com](http://tryhandlebarsjs.com) |
| for anyone who would like to try out Handlebars.js in their browser. |
| * [jQuery plugin](http://71104.github.io/jquery-handlebars/): allows you to use |
| Handlebars.js with [jQuery](http://jquery.com/). |
| * [Lumbar](http://walmartlabs.github.io/lumbar) provides easy module-based template management for |
| handlebars projects. |
| * [Marionette.Handlebars](https://github.com/hashchange/marionette.handlebars) adds support for Handlebars and Mustache templates to Marionette. |
| * [sammy.js](http://github.com/quirkey/sammy) by Aaron Quint, a.k.a. quirkey, |
| supports Handlebars.js as one of its template plugins. |
| * [SproutCore](http://www.sproutcore.com) uses Handlebars.js as its main |
| templating engine, extending it with automatic data binding support. |
| * [YUI](http://yuilibrary.com/yui/docs/handlebars/) implements a port of handlebars |
| * [Swag](https://github.com/elving/swag) by [@elving](https://github.com/elving) is a growing collection of helpers for handlebars.js. Give your handlebars.js templates some swag son! |
| * [DOMBars](https://github.com/blakeembrey/dombars) is a DOM-based templating engine built on the Handlebars parser and runtime **DEPRECATED** |
| * [promised-handlebars](https://github.com/nknapp/promised-handlebars) is a wrapper for Handlebars that allows helpers to return Promises. |
| * [just-handlebars-helpers](https://github.com/leapfrogtechnology/just-handlebars-helpers) A fully tested lightweight package with common Handlebars helpers. |
| |
| External Resources |
| ------------------ |
| |
| * [Gist about Synchronous and asynchronous loading of external handlebars templates](https://gist.github.com/2287070) |
| |
| Have a project using Handlebars? Send us a [pull request][pull-request]! |
| |
| License |
| ------- |
| Handlebars.js is released under the MIT license. |
| |
| [pull-request]: https://github.com/wycats/handlebars.js/pull/new/master |
