AMP

amp-list

Fetches content dynamically from a CORS JSON endpoint and renders it using a supplied template.

Required Script<script async custom-element="amp-list" src="https://cdn.ampproject.org/v0/amp-list-0.1.js"></script>
Supported Layoutsfill, fixed, fixed-height, flex-item, nodisplay, responsive
ExamplesSee AMP By Example's amp-list example.

Usage

The <amp-list> component fetches dynamic content from a CORS JSON endpoint. The response from the endpoint contains data, which is rendered in the specified template.

Your endpoint must implement the requirements specified in the CORS Requests in AMP spec.

You can specify a template in one of two ways:

  • a template attribute that references an ID of an existing templating element.
  • a templating element nested directly inside the amp-list element.

For more details on templates, see AMP HTML Templates.

Example: Displaying a dynamic list

In the following example, we retrieve JSON data that contains URLs and titles, and render the content in a nested amp-mustache template.

Show full code

Here is the JSON file that we used:

{
 "items": [
   {
     "title": "AMP YouTube Channel",
     "url": "https://www.youtube.com/channel/UCXPBsjgKKG2HqsKBhWA4uQw"
   },
   {
     "title": "AMPproject.org",
     "url": "https://www.ampproject.org/"
   },
   {
     "title": "AMP By Example",
     "url": "https://ampbyexample.com/"
   },
   {
     "title": "AMP Start",
     "url": "https://ampstart.com/"
   }
 ]
}

Here is how we styled the content fetched:

    amp-list div[role="list"] {
      display: grid;
      grid-gap: 0.5em;
    }

Behavior

The request is always made from the client, even if the document was served from the AMP Cache. Loading is triggered using normal AMP rules depending on how far the element is from the current viewport.

If <amp-list> needs more space after loading, it requests the AMP runtime to update its height using the normal AMP flow. If the AMP runtime cannot satisfy the request for the new height, it will display the overflow element when available. Notice however, that the typical placement of <amp-list> elements at the bottom of the document almost always guarantees that the AMP runtime can resize them.

By default, <amp-list> adds a list ARIA role to the list element and a listitem role to item elements rendered via the template.

XHR batching

AMP batches XMLHttpRequests (XHRs) to JSON endpoints, that is, you can use a single JSON data request as a data source for multiple consumers (e.g., multiple <amp-list> elements) on an AMP page. For example, if your <amp-list> makes an XHR to an endpoint, while the XHR is in flight, all subsequent XHRs to the same endpoint won't trigger and will instead return the results from the first XHR.

In <amp-list>, you can use the items attribute to render a subset of the JSON response, allowing you to have multiple <amp-list> elements rendering different content but sharing a single XHR.

Specifying an overflow

Optionally, the <amp-list> element can contain an element with an overflow attribute. This element is shown if the AMP Runtime cannot resize the <amp-list> element as requested.

Example: Displaying an overflow when the list needs more space

In the following example, we display a list of images and titles. Because the <amp-list> content requires more space than available, the AMP Runtime displays the overflow element.

Show full code

Here's the CSS for the overflow:

.list-overflow[overflow] {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
}

Placeholder and fallback

Optionally, <amp-list> supports a placeholder and/or fallback.

  • A placeholder is a child element with the placeholder attribute. This element is shown until the <amp-list> loads successfully. If a fallback is also provided, the placeholder is hidden when the <amp-list> fails to load.
  • A fallback is a child element with the fallback attribute. This element is shown if the <amp-list> fails to load.

Learn more in Placeholders & Fallbacks. Note that a child element cannot be both a placeholder and a fallback.

<amp-list src="https://foo.com/list.json">
  <div placeholder>Loading ...</div>
  <div fallback>Failed to load data.</div>
</amp-list>

Refreshing data

The <amp-list> element exposes a refresh action that other elements can reference in on="tap:..." attributes.

<button on="tap:myList.refresh">Refresh List</button>
<amp-list id="myList" src="https://foo.com/list.json">
  <template type="amp-mustache">
    <div>{{title}}</div>
  </template>
</amp-list>

Dynamic resizing

In several cases, we may need the <amp-list> to resize on user interaction. For example, when the <amp-list> contains an amp-accordion that a user may tap on, when the contents of the <amp-list> change size due to bound CSS classes, or when the number of items inside an <amp-list> changes due to a bound [src] attribute. The changeToLayoutContainer action handles this by changing the amp list to layout="CONTAINER" when triggering this action. See the following example:

  <button on="list.changeToLayoutContainer()">Show Grid</button>
  <amp-list id="list"
    width="396" height="80" layout="responsive"
    src="/test/manual/amp-list-data.json?RANDOM">
    <template type="amp-mustache">
      {{title}}
    </template>
  </amp-list>

Attributes

src (required)

The URL of the remote endpoint that returns the JSON that will be rendered within this <amp-list>. This must be a CORS HTTP service. The URL's protocol must be HTTPS.

Your endpoint must implement the requirements specified in the CORS Requests in AMP spec.

The src attribute may be omitted if the [src] attribute exists.

If fetching the data at the src URL fails, the <amp-list> triggers a low-trust fetch-error event.

credentials (optional)

Defines a credentials option as specified by the Fetch API.

  • Supported values: omit, include
  • Default: omit

To send credentials, pass the value of include. If this value is set, the response must follow the AMP CORS security guidelines.

Here's an example that specifies including credentials to display personalized content in a list:

<amp-list credentials="include"
    src="<%host%>/json/product.json?clientId=CLIENT_ID(myCookieId)">
  <template type="amp-mustache">
    Your personal offer: ${{price}}
  </template>
</amp-list>
items (optional)

Defines the expression to locate the array to be rendered within the response. This is a dot-notated expression that navigates via fields of the JSON response. By defaut <amp-list> expects an array, the single-item attribute may be used to load data from an object.

  • The default value is "items". The expected response: {items: [...]}.
  • If the response itself is the desired array, use the value of ".". The expected response is: [...].
  • Nested navigation is permitted (e.g., "field1.field2"). The expected response is: {field1: {field2: [...]}}.

When items="items" is specified (which, is the default) the response must be a JSON object that contains an array property called "items":

{
  "items": [...]
}
max-items (optional)

An integer value specifying the maximum length of the items array to be rendered. The items array will be truncated to max-items entries if the returned value exceeds max-items.

single-item (optional)

Causes <amp-list> to treat the returned result as if it were a single element array. An object response will be wrapped in an array so {items: {...}} will behave as if it were {items: [{...}]}.

reset-on-refresh (optional)

Displays a loading indicator and placeholder again when the list's source is refreshed via amp-bind or the refresh() action.

By default, this will only trigger on refreshes that cause a network fetch. To reset on all refreshes, use reset-on-refresh="always".

binding (optional)

For pages using <amp-list> that also use amp-bind, controls whether or not to block render on the evaluation of bindings (e.g. [text]) in rendered children.

We recommend using binding="no" or binding="refresh" for faster performance.

  • binding="no": Never block render (fastest).
  • binding="refresh": Don't block render on initial load (faster).
  • binding="always": Always block render (slow).

If binding attribute is not provided, default is always.

[is-layout-container] (optional)

This is a bindable attribute that should always be false by default. When set to true via amp-bind, it changes the layout of the <amp-list> to container. This attribute is useful for handling dynamic resizing for amp-list.

This attribute cannot be true by default for the same reason why <amp-list> does not support layout CONTAINER — it can cause content jumping on first load.

Alternatively, one may also use the changeToLayoutContainer action.

common attributes

This element includes common attributes extended to AMP components.

Load more and infinite scroll

We've introduced the load-more attributes with options manual and auto to allow pagination and infinite scroll.

Sample Usage

<amp-list load-more="auto" src="https://my.rest.endpoint/" width="100" height="200">
  <template type="amp-mustache">
  // ...
  </template>
</amp-list>

For working examples, please see test/manual/amp-list/infinite-scroll-1.amp.html and test/manual/amp-list/infinite-scroll-2.amp.html.

Attributes

load-more (mandatory)

This attribute accepts two values: "auto" or "manual". Setting the value of this attribute to "manual" will show a "load-more" button at the end of <amp-list>. Setting the value of this attribute to "auto" will cause <amp-list> to automatically load more elements three viewports down for an infinite scroll effect.

load-more-bookmark (optional)

This attribute specifies a field name in the returned data that will give the url of the next items to load. If this attribute is not specified, <amp-list> expects the json payload to have the load-more-src field, which corresponds to the next url to load. In the case where this field is called something else, you can specify the name of that field via the load-more-bookmark field.E.g. In the following sample payload, we would specify load-more-bookmark="next".

{ "items": [...], "next": "https://url.to.load" }

Customizing load-more elements

<amp-list> with the load-more attribute contains these UI elements: a load-more button, a loader, a load-failed element, and optionally an end-cap marking the end of the list. These elements can be customized by providing <amp-list-load-more> elements as children of <amp-list> with the following attributes:

load-more-button

An <amp-list-load-more> element with the load-more-button attribute, which shows up at the end of the list (for the manual load-more) if there are more elements to be loaded. Clicking on this element will trigger a fetch to load more elements from the url contained in the load-more-src field or the field of the data returned corresponding to the load-more-bookmark attribute. This element can be customized by providing <amp-list> with a child element that has the attribute load-more-button.

Example:
<amp-list load-more="manual" src="https://www.load.more.example.com/" width="400" height="800">
  ...
  <amp-list-load-more load-more-button>
    <button>See More</button> /* My custom see more button */
  </amp-list-load-more>
</amp-list>

It can be templated via amp-mustache.

Example:
<amp-list load-more="auto" width="100" height="500" src="https://www.load.more.example.com/">
  ...
  <amp-list-load-more load-more-button>
    <template type="amp-mustache">
      Showing {{#count}} out of {{#total}} items
      <button>
        Click here to see more!
      </button>
    </template>
  </amp-list-load-more>
</amp-list>

load-more-loading

This element is a loader that will be displayed if the user reaches the end of the list and the contents are still loading, or as a result of clicking on the load-more-button element (while the new children of the <amp-list> are still loading). This element can be customized by providing <amp-list> with a child element that has the attribute load-more-loading. Example below:

<amp-list load-more="auto" src="https://www.load.more.example.com/" width="400" height="800">
  ...
  <amp-list-load-more load-more-loading>
    <svg>...</svg> /* My custom loader */
  </amp-list-load-more>
</amp-list>

load-more-failed

A <amp-list-load-more> element containing the load-more-failed attribute that contains a button with the load-more-clickable attribute that will be displayed at the bottom of the <amp-list> if loading failed. Clicking on this element will trigger a reload of the url that failed. This element can be customized by providing <amp-list> with a child element that has the attribute load-more-failed. Example below:

<amp-list load-more="auto" src="https://www.load.more.example.com/" width="200" height="500">
  ...
  <amp-list-load-more load-more-failed>
    <button>Unable to Load More</button>
  </amp-list-load-more>
</amp-list>

In the above example, the entire load-more-failed element is clickable. However, a common pattern for this element is a general unclickable "loading failed" element that contains a clickable "reload" button. To account for this, you can have a generally unclickable element with a button containing the load-more-clickable element. For example:

<amp-list load-more="auto" src="https://www.load.more.example.com/" width="200" height="500">
  ...
  <amp-list-load-more load-more-failed>
    <div>
      Here is some unclickable text saying sorry loading failed.
    </div>
    <button load-more-clickable>Click me to reload!</button>
  </amp-list-load-more>
</amp-list>

load-more-end

This element is not provided by default, but if a <amp-list-load-more> element containing the load-more-end attribute is attached to <amp-list> as a child element, this element will be displayed at the bottom of the <amp-list> if there are no more items. This element can be templated via amp-mustache. Example below:

<amp-list load-more="auto" src="https://www.load.more.example.com/" width="200" height="500">
  ...
  <amp-list-load-more load-more-end>
    Congratulations! You've reached the end. /* Custom load-end element */
  </amp-list-load-more>
</amp-list>

Substitutions

The <amp-list> allows all standard URL variable substitutions. See the Substitutions Guide for more info.

For example:

<amp-list src="https://foo.com/list.json?RANDOM"></amp-list>

may make a request to something like https://foo.com/list.json?0.8390278471201 where the RANDOM value is randomly generated upon each impression.

Validation

See amp-list rules in the AMP validator specification.

Need more help?

You've read this document a dozen times but it doesn't really cover all of your questions? Maybe other people felt the same: reach out to them on Stack Overflow.

Go to Stack Overflow
Found a bug or missing a feature?

The AMP project strongly encourages your participation and contributions! We hope you'll become an ongoing participant in our open source community but we also welcome one-off contributions for the issues you're particularly passionate about.

Go to GitHub