Mustache Endpoints

Learn how to use Mustache to create HTML views.


Stacklane uses Mustache, combined with additional extensions (pragmas), to create dynamic HTML views.

To use Mustache to generate HTML views, continue to use the ".html" extension, and on the first line of the HTML file use the special comment:

<!--TEMPLATE mustache-->

All files that use Mustache for the templating language, including partials/imports, must include on the first line.

Mustache views may be populated with data or other scripted variables by importing variables previously exported by Suppliers.


Mustache endpoints are routed according to their file name.

For example, /hello/world.html responds to requests for GET /hello/world.

index.html may be used in the case where the routing should be directory based. /hello/index.html responses to requests for GET /hello/. Note: It will also respond to requests for GET /hello (no trailing slash), and redirect to the actual endpoint of /hello/ (trailing slash).

Link Absolute Paths

When referencing files or endpoints within your app we highly recommend using "href" and "src" with absolute values instead of relative values -- href="/here/there" instead of href="here/there".

This creates consistency in a number of other locations including script redirects, Mustache partial imports, and in general leaves no ambiguity.


Mustache partials may be thought of as file includes. The syntax for including a partial is {{> nameOfPartial}}.

By default there are no partials available. Stacklane uses pragmas to instruct what partials are available, and how they are named.

Directory of Partials

Name the directory with a leading underscore to indicate it is private: /_partials/. To allow the individual Mustache files in the directory to be used as partials, use the pragma {{% partial /_partials/ }} (note the trailing slash). Given a file in this directory /_partials/something.html, it may then be included via the standard syntax {{> something}}.

A directory of partials may optionally be given a prefix. Using the above example, {{% partial /_partials/ as my}} brings in those partials with the "my-" prefix (hyphen is implied). The same partial is now included using {{> my-something}}

Single Files

A single partial may be imported by referencing its full path name without the ".html" extension. {{% partial /_partials/something }} is accessible via {{> something}}.

Single file partials also support aliases. {{% partial /_something as somethingElse }} is accessible via {{> somethingElse}}.


SVG files may be included/inlined using the same nomenclature as Mustache partials. The only difference is the initial pragma.

Given a directory of SVG icons, the pragma {{% svg /_icons/ as ic }} would allow importing of gear.svg using {{> ic-gear}}.

Layout Templates

A common extension to Mustache is the ability to define a "master template". This file contains the <html>, <head>, and <body> tags. Within the file there is at least one placeholder which denotes where to "insert" a section of HTML from another Mustache file (the file which uses this master layout template).

Master Template

<!--TEMPLATE mustache-->
<!DOCTYPE html>

Template Using Layout

The file using the master layout template will include it similar to a partial. Assuming a layout file named /_layout.html, another file would use this template like:

<!--TEMPLATE mustache-->
{{% partial /_layout}}

{{$title}}My Title{{/title}}
.. Custom Content Here ..


In certain cases it helps to keep structured data outside of your Mustache file, and then include this for processing as any other variable. This might make sense when a model type is overkill, or its specs are still being mocked up.

In this case you can define a JSON file with a list of objects, and then refer to it as you would any partial: {{% json /_myData as myData }}. This list of objects may then be iterated using Mustache iteration tags.



Provides a declarative way to choose one string based on another string. If it were defined programmatically it would be a series of simple if/then/else, or switch/case/default statements. This is especially useful when dealing with constant, well-defined values for a model field.

First, declare the string choices using choose-string-map.

{{% choose-string-map message error=alert-danger *=alert-* }}

The first parameter of message defines a name of the string choice, which will be repeated later for choose-string. The remaining parameters define the mapping of input strings to output strings, with an optional capture of the input via "*".

The above example outputs "alert-danger" when the string input is "error". A catch all / else case may defined with "*". In the example above an input of "success" would result in "alert-success". For any of the cases, "*" is available to fill in the existing string input.

Second, use the previously defined string map. The first parameter repeats the name given to the string map, and the second parameter is the string input.

<div class="notification {{% choose-string message this.type }}">

Alternative Definition

choose-string-map is the most compact way to define the choices. However if spaces are needed in the strings use JSON for the definition via choose-string-json.

{{% choose-string-json message
    "error": "alert alert-danger",
     "*": "alert alert-*"

Iteration Extensions

We've extended Mustache iteration with a couple of helpful utilities. Standard mustache iteration looks like {{#SomeList}} ... {{/SomeList}}. There are two additional iteration options:


Use 'as' to rename the internal variable available in each iteration: {{#SomeList as item}} {{item.prop}} {{/SomeList}}


Use 'by' to iterate the collection in groups of N (up to 10). This is most useful when working with various CSS grid layouts.

{{#SomeList by 2 as grp}}
    {{#grp as item}}

Variable Imports

Mustache views may import variables which were exported by Suppliers. To import a variable (or variables) use the following pragma:

{{% import {SomeVar, AnotherVar} from '📤' }}

After importing, {{SomeVar}} may then be used anywhere within the Mustache view.

(As mentioned in the documentation on Suppliers, all variables exported exist in the module '📤'.)

HTML Encoding/Escapes

Mustache escapes / encodes special HTML characters by default when they are included from a variable or model field. If {{}} is "ABC & Co.", then this will become the encoded HTML equivalent ABC &amp; Co..

Separation of Concerns

If there are developers on a team who are strictly working on Mustache views, it may be useful to limit their access to specific Supplier values.

This can be accomplished by creating a pinned supplier file within the same directory as the Mustache view.

For example, given a Mustache view of /hello/world.html, and a Supplier file of /hello/📤📌world.js, the Mustache view will only have access to values exported by /hello/📤📌world.js, regardless of any other Supplier's in the path.

Content Security Policies (CSP)

All pages served by Stacklane are given a Content Security Policy (CSP). The CSP header allows a host to declare trusted sources of content (JS execution, CSS styles, images etc).

Automatic Behavior

Files are analyzed to create a reasonable CSP file.

  • <script src=" ... >
  • <link rel="stylesheet" href=" ... >
  • Inline <script> elements become a CSP hash source.
  • Inline <style> elements become a CSP hash source.

Custom Declarations

Include the following tag anywhere in the body:

<link itemprop="content-security-policy" ... >
This tag supports the following properties:
  • data-connect-self="true" - allows AJAX connections to the same web app.
  • data-img-src-data="true" - allows "data:" as an image source in CSS.


  • Inline style attributes style="..." are not allowed.
  • Inline JavaScript via attributes onclick="...", etc, are not allowed.