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API Fragment placement

This page outlines various ways to place new fragments in your existing DOM tree.

Swapping fragments

Pass a CSS selector like { target: '.content' } to replace an existing element with a new version, usually fetched from the server via HTTP.

The server may return additional HTML, but only the element matching the selector is used. All other HTML from the server response is discarded.

Interaction origin is considered

When a link or form updates a fragment, Unpoly will prefer to match fragments in the vicinity of that link or form element.

For example, assume we have two links that replace .card:

<div class="card">
  Card #1 preview
  <a href="/cards/1" up-target=".card">Show full card #1</a>

<div class="card">
  Card #2 preview
  <a href="/cards/2" up-target=".card">Show full card #2</a>

When clicking on "Show full card #2", Unpoly will replace the second card.

The interaction origin can only be considered in the current page, but not in the server response. In the example above the server is expected to only render a single .card element.

See up.fragment.get() for more examples and advanced use cases.

Updating multiple fragments

You can update multiple fragments from a single request by separating separators with a comma (like in CSS).

For instance, if opening a post should also update a bubble showing the number of unread posts, you might do this:

<a href="/posts/5" up-target=".content, .unread-count">Read post</a>

Appending or prepending content

By default Unpoly will replace the given selector with the same selector from the server response. Instead of replacing you can append the loaded content to the existing content by using the :after pseudo selector. In the same fashion, you can use :before to prepend the loaded content.

A practical example would be a paginated list of items. Below the list is a button to load the next page. You can append to the existing list by using :after in the [up-target] selector like this:

<ul class="tasks">
  <li>Wash car</li>
  <li>Purchase supplies</li>
  <li>Fix tent</li>

<a href="/page/2" class="next-page" up-target=".tasks:after, .next-page">
  Load more tasks

Replacing an element's inner HTML

If you would like to preserve the target element, but replace all of its child content, use the :content pseudo selector:

<a href="/cards/5" up-target=".card:content">Show card #5</a>

For more advanced cases of preserving elements, see [up-keep].

Rendering nothing

To make a server request without changing a fragment, use the :none selector:

<a href="/ping" up-target=":none">Ping server</a>
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