The `client-side-templates` Extension

This extension supports transforming a JSON/XML request response into HTML via a client-side template before it is swapped into the DOM. Currently four client-side templating engines are supported:

When you add this extension on an element, any element below it in the DOM can use one of four attributes named <template-engine>-template (e.g. mustache-template) with a template ID, and the extension will resolve and render the template the standard way for that template engine:

mustache - looks a mustache <script> tag up by ID for the template content
handlebars - looks a handlebars <script> tag up by ID for the template content
nunjucks - resolves the template by name via `nunjucks.render()
xslt - looks an XSLT <script> tag up by ID for the template content

The AJAX response body will be parsed as JSON/XML and passed into the template rendering.

A second “array” version of each template is now offered, which is particularly helpful for APIs that return arrays of data. These templates are referenced as <template-engine>-array-template, and the data is accessed as data.my_server_field. At least in the case of mustache, it also enables use of loops using the {{#data}} my_server_field {{/data}} syntax.

#Install

<script src="https://unpkg.com/htmx.org@1.9.12/dist/ext/client-side-templates.js"></script>

#Usage

<div hx-ext="client-side-templates">
  <button hx-get="/some_json"
          mustache-template="my-mustache-template">
     Handle with mustache
  </button>
  <button hx-get="/some_json"
          handlebars-template="my-handlebars-template">
     Handle with handlebars
  </button>
  <button hx-get="/some_json"
          nunjucks-template="my-nunjucks-template">
     Handle with nunjucks
  </button>
  <button hx-get="/some_xml" 
          xslt-template="my-xslt-template">
     Handle with XSLT
  </button>
</div>

#Full Mustache HTML Example

To use the client side template, you will need to include htmx, the extension, and the rendering engine. Here is an example of this setup for Mustache using a <template> tag.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
  <script src="https://unpkg.com/htmx.org"></script>
  <script src="https://unpkg.com/htmx.org@1.9.12/dist/ext/client-side-templates.js"></script>
  <script src="https://unpkg.com/mustache@latest"></script>
</head>
<body>
  <div hx-ext="client-side-templates">
    <button hx-get="https://jsonplaceholder.typicode.com/todos/1"
            hx-swap="innerHTML"
            hx-target="#content"
            mustache-template="foo">
      Click Me
    </button>

    <p id="content">Start</p>

    <template id="foo">
      <p> {% raw %}{{userID}}{% endraw %} and {% raw %}{{id}}{% endraw %} and {% raw %}{{title}}{% endraw %} and {% raw %}{{completed}}{% endraw %}</p>
    </template>
  </div>
</body>
</html>

Here is a jsbin playground to try this out.

Here’s a working example using the mustache-array-template working against an API that returns an array:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
  <script src="https://unpkg.com/htmx.org"></script>
  <script src="https://unpkg.com/htmx.org@1.9.12/dist/ext/client-side-templates.js"></script>
  <script src="https://unpkg.com/mustache@latest"></script>
</head>
<body>
  <div hx-ext="client-side-templates">
    <button hx-get="https://jsonplaceholder.typicode.com/users"
            hx-swap="innerHTML"
            hx-target="#content"
            mustache-array-template="foo">
      Click Me
    </button>

    <p id="content">Start</p>

    <template id="foo">
      {{#data}}
      <p> {{name}} at {{email}} is with {{company.name}}</p>
      {{/data}}
    </template>
  </div>
</body>
</html>

#Full XSLT HTML Example

To use the client side template, you will need to include htmx and the extension. Here is an example of this setup for XSLT using a <script> tag.

If you wish to put a template into another file, you can use a directive such as <object id="template-id" data="my-template.xml" style="position: absolute; bottom: 0px; width: 0px; height: 0px;">. Some styling is needed to keep the object visible while not taking any space.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
  <script src="https://unpkg.com/htmx.org"></script>
  <script src="https://unpkg.com/htmx.org@1.9.12/dist/ext/client-side-templates.js"></script>
</head>
<body>
  <div hx-ext="client-side-templates">
    <button hx-get="http://restapi.adequateshop.com/api/Traveler"
            hx-swap="innerHTML"
            hx-target="#content"
            xslt-template="foo">
      Click Me
   </button>

    <p id="content">Start</p>

    <script id="foo" type="application/xml">
      <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
        <xsl:template match="/">
          page <xsl:value-of select="/TravelerinformationResponse/page" /> of <xsl:value-of select="/TravelerinformationResponse/total_pages" />
        </xsl:template>
      </xsl:stylesheet>
    </script>
  </div>
</body>
</html>

#CORS and REST/JSON

As a warning, many web services use CORS protection and/or other protection schemes to reject a REST/JSON request from a web browser - for example, GitHub will issue a CORS error if you try to use the above snippet to access public APIs. This can be frustrating, as a dedicated REST development client may work fine, but the CORS error will appear when running JavaScript. This doesn’t really have anything to do with HTMX (as you’d have the same issues with any JavaScript code), but can be a frustrating surprise.