Description 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 Layouts fill, fixed, fixed-height, flex-item, nodisplay, responsive
Examples See 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 an array, which is rendered in the specified template.

You can specify a template in one of two ways:

  • a template attribute that references an ID of an existing template element.
  • a template 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/"
   }
 ]
}

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>

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.

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.

  • 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": [...]
}
common attributes

This element includes common attributes extended to AMP components.

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.