document.185

# mustache.js - Logic-less {{mustache}} templates with JavaScript

> What could be more logical awesome than no logic at all?

[![Build Status](https://travis-ci.org/janl/mustache.js.svg?branch=master)](https://travis-ci.org/janl/mustache.js) [![Gitter chat](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/janl/mustache.js)

[mustache.js](http://github.com/janl/mustache.js) is an implementation of the [mustache](http://mustache.github.com/) template system in JavaScript.

[Mustache](http://mustache.github.com/) is a logic-less template syntax. It can be used for HTML, config files, source code - anything. It works by expanding tags in a template using values provided in a hash or object.

We call it "logic-less" because there are no if statements, else clauses, or for loops. Instead there are only tags. Some tags are replaced with a value, some nothing, and others a series of values.

For a language-agnostic overview of mustache's template syntax, see the `mustache(5)` [manpage](http://mustache.github.com/mustache.5.html).

## Where to use mustache.js?

You can use mustache.js to render mustache templates anywhere you can use JavaScript. This includes web browsers, server-side environments such as [node](http://nodejs.org/), and [CouchDB](http://couchdb.apache.org/) views.

mustache.js ships with support for both the [CommonJS](http://www.commonjs.org/) module API and the [Asynchronous Module Definition](https://github.com/amdjs/amdjs-api/wiki/AMD) API, or AMD.

And this will be your templates after you use Mustache:

!['stache](https://cloud.githubusercontent.com/assets/288977/8779228/a3cf700e-2f02-11e5-869a-300312fb7a00.gif)

## Install

You can get Mustache via npm.

```bash
$ npm install mustache --save
```
or install with bower:

```bash
$ bower install --save mustache
```

## Command line tool

mustache.js is shipped with a node based command line tool. It might be installed as a global tool on your computer to render a mustache template of some kind

```bash
$ npm install -g mustache

$ mustache dataView.json myTemplate.mustache > output.html
```

also supports stdin.

```bash
$ cat dataView.json | mustache - myTemplate.mustache > output.html
```

or as a package.json `devDependency` in a build process maybe?

```bash
$ npm install mustache --save-dev
```

```json
{
  "scripts": {
    "build": "mustache dataView.json myTemplate.mustache > public/output.html"
  }
}
```
```bash
$ npm run build
```

The command line tool is basically a wrapper around `Mustache.render` so you get all the features.

If your templates use partials you should pass paths to partials using `-p` flag:

```bash
$ mustache -p path/to/partial1.mustache -p path/to/partial2.mustache dataView.json myTemplate.mustache
```

## Who uses mustache.js?

An updated list of mustache.js users is kept [on the Github wiki](http://wiki.github.com/janl/mustache.js/beard-competition). Add yourself or your company if you use mustache.js!

## Contributing

mustache.js is a mature project, but it continues to actively invite maintainers. You can help out a high-profile project that is used in a lot of places on the web. There is [plenty](https://github.com/janl/mustache.js/issues) of [work](https://github.com/janl/mustache.js/pulls) to do. No big commitment required, if all you do is review a single [Pull Request](https://github.com/janl/mustache.js/pulls), you are a maintainer. And a hero.

### Your First Contribution

- review a [Pull Request](https://github.com/janl/mustache.js/pulls)
- fix an [Issue](https://github.com/janl/mustache.js/issues)
- update the [documentation](https://github.com/janl/mustache.js#usage)
- make a website
- write a tutorial

* * *

## Usage

Below is a quick example how to use mustache.js:

```js
var view = {
  title: "Joe",
  calc: function () {
    return 2 + 4;
  }
};

var output = Mustache.render("{{title}} spends {{calc}}", view);
```

In this example, the `Mustache.render` function takes two parameters: 1) the [mustache](http://mustache.github.com/) template and 2) a `view` object that contains the data and code needed to render the template.

## API

Following is an [rtype](https://git.io/rtype) signature of the most commonly used functions.

```js
Mustache.render(
  template  : String,
  view      : Object,
  partials? : Object,
) => String

Mustache.parse(
  template              : String,
  tags = ['{{', '}}']   : Tags,
) => String

interface Tags [String, String]
```

## Templates

A [mustache](http://mustache.github.com/) template is a string that contains any number of mustache tags. Tags are indicated by the double mustaches that surround them. `{{person}}` is a tag, as is `{{#person}}`. In both examples we refer to `person` as the tag's key. There are several types of tags available in mustache.js, described below.

There are several techniques that can be used to load templates and hand them to mustache.js, here are two of them:

#### Include Templates

If you need a template for a dynamic part in a static website, you can consider including the template in the static HTML file to avoid loading templates separately. Here's a small example using `jQuery`:

```html
<html>
<body onload="loadUser">
<div id="target">Loading...</div>
<script id="template" type="x-tmpl-mustache">
Hello {{ name }}!
</script>
</body>
</html>
```

```js
function loadUser() {
  var template = $('#template').html();
  Mustache.parse(template);   // optional, speeds up future uses
  var rendered = Mustache.render(template, {name: "Luke"});
  $('#target').html(rendered);
}
```

#### Load External Templates

If your templates reside in individual files, you can load them asynchronously and render them when they arrive. Another example using `jQuery`:

```js
function loadUser() {
  $.get('template.mst', function(template) {
    var rendered = Mustache.render(template, {name: "Luke"});
    $('#target').html(rendered);
  });
}
```

### Variables

The most basic tag type is a simple variable. A `{{name}}` tag renders the value of the `name` key in the current context. If there is no such key, nothing is rendered.

All variables are HTML-escaped by default. If you want to render unescaped HTML, use the triple mustache: `{{{name}}}`. You can also use `&` to unescape a variable.

If you want `{{name}}` _not_ to be interpreted as a mustache tag, but rather to appear exactly as `{{name}}` in the output, you must change and then restore the default delimiter. See the ["Set Delimiter"](https://github.com/janl/mustache.js#set-delimiter) section for more information about custom delimiters.

View:

```json
{
  "name": "Chris",
  "company": "<b>GitHub</b>"
}
```

Template:

```
* {{name}}
* {{age}}
* {{company}}
* {{{company}}}
* {{&company}}
{{=<% %>=}}
* {{company}}
<%={{ }}=%>
```

Output:

```html
* Chris
*
* &lt;b&gt;GitHub&lt;/b&gt;
* <b>GitHub</b>
* <b>GitHub</b>
* {{company}}
```

JavaScript's dot notation may be used to access keys that are properties of objects in a view.

View:

```json
{
  "name": {
    "first": "Michael",
    "last": "Jackson"
  },
  "age": "RIP"
}
```

Template:

```html
* {{name.first}} {{name.last}}
* {{age}}
```

Output:

```html
* Michael Jackson
* RIP
```

### Sections

Sections render blocks of text one or more times, depending on the value of the key in the current context.

A section begins with a pound and ends with a slash. That is, `{{#person}}` begins a `person` section, while `{{/person}}` ends it. The text between the two tags is referred to as that section's "block".

The behavior of the section is determined by the value of the key.

#### False Values or Empty Lists

If the `person` key does not exist, or exists and has a value of `null`, `undefined`, `false`, `0`, or `NaN`, or is an empty string or an empty list, the block will not be rendered.

View:

```json
{
  "person": false
}
```

Template:

```html
Shown.
{{#person}}
Never shown!
{{/person}}
```

Output:

```html
Shown.
```

#### Non-Empty Lists

If the `person` key exists and is not `null`, `undefined`, or `false`, and is not an empty list the block will be rendered one or more times.

When the value is a list, the block is rendered once for each item in the list. The context of the block is set to the current item in the list for each iteration. In this way we can loop over collections.

View:

```json
{
  "stooges": [
    { "name": "Moe" },
    { "name": "Larry" },
    { "name": "Curly" }
  ]
}
```

Template:

```html
{{#stooges}}
<b>{{name}}</b>
{{/stooges}}
```

Output:

```html
<b>Moe</b>
<b>Larry</b>
<b>Curly</b>
```

When looping over an array of strings, a `.` can be used to refer to the current item in the list.

View:

```json
{
  "musketeers": ["Athos", "Aramis", "Porthos", "D'Artagnan"]
}
```

Template:

```html
{{#musketeers}}
* {{.}}
{{/musketeers}}
```

Output:

```html
* Athos
* Aramis
* Porthos
* D'Artagnan
```

If the value of a section variable is a function, it will be called in the context of the current item in the list on each iteration.

View:

```js
{
  "beatles": [
    { "firstName": "John", "lastName": "Lennon" },
    { "firstName": "Paul", "lastName": "McCartney" },
    { "firstName": "George", "lastName": "Harrison" },
    { "firstName": "Ringo", "lastName": "Starr" }
  ],
  "name": function () {
    return this.firstName + " " + this.lastName;
  }
}
```

Template:

```html
{{#beatles}}
* {{name}}
{{/beatles}}
```

Output:

```html
* John Lennon
* Paul McCartney
* George Harrison
* Ringo Starr
```

#### Functions

If the value of a section key is a function, it is called with the section's literal block of text, un-rendered, as its first argument. The second argument is a special rendering function that uses the current view as its view argument. It is called in the context of the current view object.

View:

```js
{
  "name": "Tater",
  "bold": function () {
    return function (text, render) {
      return "<b>" + render(text) + "</b>";
    }
  }
}
```

Template:

```html
{{#bold}}Hi {{name}}.{{/bold}}
```

Output:

```html
<b>Hi Tater.</b>
```

### Inverted Sections

An inverted section opens with `{{^section}}` instead of `{{#section}}`. The block of an inverted section is rendered only if the value of that section's tag is `null`, `undefined`, `false`, *falsy* or an empty list.

View:

```json
{
  "repos": []
}
```

Template:

```html
{{#repos}}<b>{{name}}</b>{{/repos}}
{{^repos}}No repos :({{/repos}}
```

Output:

```html
No repos :(
```

### Comments

Comments begin with a bang and are ignored. The following template:

```html
<h1>Today{{! ignore me }}.</h1>
```

Will render as follows:

```html
<h1>Today.</h1>
```

Comments may contain newlines.

### Partials

Partials begin with a greater than sign, like {{> box}}.

Partials are rendered at runtime (as opposed to compile time), so recursive partials are possible. Just avoid infinite loops.

They also inherit the calling context. Whereas in ERB you may have this:

```html+erb
<%= partial :next_more, :start => start, :size => size %>
```

Mustache requires only this:

```html
{{> next_more}}
```

Why? Because the `next_more.mustache` file will inherit the `size` and `start` variables from the calling context. In this way you may want to think of partials as includes, imports, template expansion, nested templates, or subtemplates, even though those aren't literally the case here.


For example, this template and partial:

    base.mustache:
    <h2>Names</h2>
    {{#names}}
      {{> user}}
    {{/names}}

    user.mustache:
    <strong>{{name}}</strong>

Can be thought of as a single, expanded template:

```html
<h2>Names</h2>
{{#names}}
  <strong>{{name}}</strong>
{{/names}}
```

In mustache.js an object of partials may be passed as the third argument to `Mustache.render`. The object should be keyed by the name of the partial, and its value should be the partial text.

```js
Mustache.render(template, view, {
  user: userTemplate
});
```