Hubert
9 min
May 8, 2024

What is Mustache.js?

Mustache.js is a lightweight JavaScript template library that uses a "logic-less template syntax." This means that the templates do not contain programming logic, making them more transparent and easier to maintain. Mustache.js allows for the separation of HTML code from the data used to render the page, facilitating easier code management and reuse.

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What is Mustache.js?

Introduction to Mustache.js

Mustache.js is a popular JavaScript templating library that allows you to render dynamic content on the client-side. It is a logic-less template system, meaning that it does not support if statements, else clauses, or for loops. Instead, it uses a simple syntax to render templates based on the data provided.

The beauty of Mustache.js lies in its simplicity and flexibility. By separating the HTML structure from the data, it makes your code cleaner and easier to maintain. This approach also enhances reusability, as the same template can be used with different data sets. Moreover, Mustache.js is compatible with various programming languages and environments, making it a versatile tool for developers working on diverse projects.

Where can Mustache.js be used?

Mustache.js is a versatile templating engine known for its simplicity and effectiveness across various development contexts. Whether building web applications or generating content for other mediums, understanding where Mustache.js can be best utilized enhances both development flexibility and performance. Let’s explore the key areas where Mustache.js excels.

Single-Page Applications (SPAs): Mustache.js is indeed suitable for generating dynamic HTML in SPAs. It’s a logic-less template syntax that can be used to abstract HTML templates from JavaScript logic. However, it primarily handles the templating part — inserting data into HTML.

Use with frameworks: While Mustache.js can technically be used with frameworks like Angular, React, or Vue.js, it is not commonly paired with them. These frameworks already have their own powerful templating systems (e.g., JSX in React, Vue’s template syntax). Integrating Mustache.js into these ecosystems might complicate things unnecessarily as it might not leverage the reactive and component-based features these frameworks offer.

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Server-Side rendering: Mustache.js can indeed be used on the server side, particularly with Node.js, to render templates before sending them to the browser. This use is quite effective for scenarios where you want to serve fully rendered HTML for SEO purposes or to speed up initial load times. Partials in Mustache.js inherit variables from the calling context, which is crucial for understanding template expansion and the behavior of partials in rendering workflows.

Sharing templates between server and client: Mustache.js is useful in projects that require the same templates to be used on both the server and client sides. This helps in maintaining a uniform structure between client-rendered and server-rendered content, simplifying code management. Partials contribute to an expanded template that inherits context and variables from the calling template, effectively demonstrating how partials function as part of a cohesive template system.

Beyond the web: Mustache.js can also be used in non-web contexts, such as generating content for emails or documents where a simple templating mechanism is required. This is because Mustache.js is language-agnostic and can be implemented in various programming environments.

Mustache.js Mustache Templates

Mustache.js templates are simple yet powerful tools for generating HTML code or other types of documents based on data. They use special tags, which are replaced with corresponding values at the time of rendering. The basic tag type, represented as {{name}}, attempts to find a corresponding key in the current context. Below we present the basic components of Mustache.js templates and examples of their application.

The most basic tag type, represented as a {{variable}} tag, functions within a template by searching for keys in the current context. It includes a default HTML escaping mechanism to ensure safe rendering of variables.

Mustache Tags

Mustache tags are placed inside double curly braces {{}}. Here are the most commonly used tags: {{variable}} – This tag will be replaced by the value of the variable passed to the template. {{#list}} … {{/list}} – A section that is rendered multiple times depending on the number of elements in the list. {{^variable}} … {{/variable}} – A section that is rendered only when the variable is empty or false. {{! comment }} – Allows adding a comment in the template that will not be rendered.

The triple mustache {{{variable}}} syntax can be used to render unescaped HTML content, allowing raw contents to be displayed without any escaping.

Template example and template expansion

Consider a simple template that generates a to-do list:

<h1>To do list</h1>
<ul>
  {{#tasks}}
    <li>{{name}} - {{status}}</li>
  {{/tasks}}
</ul>

In the above template, tasks is an array of objects, each containing a name and status. The template renders an < li> element for each task in the list.

If a person key exists in the data, the template could render additional sections based on the value of this key. For example, if the person key is false or empty, certain HTML blocks might be omitted, whereas a non-empty list could trigger the rendering of specific sections related to the person.

Introducing data

Data is passed to the template in JSON format, which facilitates manipulation and integration with other systems. Here is an example of data for the to-do list template:

{
"tasks": [
{"name": "Shopping", "status": "Completed"},
{"name": "Learning Mustache.js", "status": "In Progress"}
]
}

At the time of rendering, Mustache.js replaces the tags in the template with the appropriate values from the provided data, generating the final HTML code. Partials can be seen as a form of template expansion because they allow for the inclusion and inheritance of variables from a parent context.

Partials and Custom Delimiters

Partials are a powerful feature in Mustache.js that allows you to render templates within templates. They are denoted by the {{> partial}} syntax and can be used to create complex templates by breaking them down into smaller, reusable pieces. This modular approach not only simplifies template management but also promotes code reuse, making your templates more maintainable.

Custom delimiters are another useful feature in Mustache.js that allows you to change the default tag style. By default, Mustache.js uses the {{ }} syntax to denote tags, but you can change this to any custom string using the {{= custom_string}} syntax. This is particularly useful when working with templates that might conflict with other templating systems or when you need to integrate Mustache.js into environments with different syntactic requirements.

Advantages and Capabilities of Mustache.js

The main advantage of Mustache.js is the clear separation of logic from presentation. This makes the code more understandable and readable, and the team works more efficiently. Mustache.js is designed for fast template rendering, which is effective both in web browsers and in server applications based on Node.js. It is an easy and intuitive tool for beginner developers, while also offering advanced capabilities. Mustache.js is a valuable tool for managing templates in web projects. Additionally, custom strings can be used to set custom delimiters for tag templating, allowing users to modify the default tag delimiters from {{ and }} to alternative formats, which is particularly useful for ensuring compatibility with certain programming languages, like TeX, that may use similar syntax in their text.

Installation and Usage

Installing Mustache.js is straightforward and can be done using npm or yarn. Simply run the following command to install the library:

For npm:

npm install mustache

For yarn:

yarn add mustache

To use Mustache.js, you need to create a template and a JavaScript object that contains the data to be rendered. You can then use the Mustache.render() function to render the template with the data.

Example:

const template = '<div>{{name}}</div>';
const data = { name: 'John Doe' };
const renderedTemplate = Mustache.render(template, data);
console.log(renderedTemplate); // Output: <div>John Doe</div>

In this example, the Mustache.render() function takes two arguments: the template string and the data object. It then returns the rendered template as a string.

You can also use Mustache.js to render templates with partials and custom delimiters. For example:

const template = '<div>{{> partial}}</div>';
const partial = '<p>{{name}}</p>';
const data = { name: 'John Doe' };
const renderedTemplate = Mustache.render(template, data, { partials: { partial } });
console.log(renderedTemplate); // Output: <div><p>John Doe</p></div>

In this example, the Mustache.render() function takes three arguments: the template string, the data object, and an options object that contains the partials. It then returns the rendered template as a string.

Overall, Mustache.js is a powerful and flexible templating library that can be used to render dynamic content on the client-side. Its simplicity, flexibility, and ease of use make it a popular choice among developers.


What is Mustache.js used for?

Mustache.js is a template engine used for dynamically rendering HTML based on data and templates. It allows for the separation of application logic from the presentation layer. The ‘set delimiter tag’ feature allows users to specify custom delimiters for tags in their templates, initiated with an equal sign, which can switch the default tag delimiters to user-defined strings. This is particularly useful for languages like TeX where the default braces may conflict with text formatting.

What is the difference between JSON and Mustache?

JSON (JavaScript Object Notation) is a data format used for storing and transmitting information in a form readable by humans and machines. Mustache is a template engine used to generate marked-up text, such as HTML, based on JSON data and Mustache templates. Tag delimiters can be customized to change the default delimiting characters from {{ and }} to other strings.

Is Mustache a logic less programming language?

No, Mustache is not a programming language. It is a template engine that allows for the creation of HTML templates or other types of documents using data in JSON format.

A mustache template is a specific format of string that contains mustache tags, which are used to render dynamic content.

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