The on attribute is used to install event handlers on elements. The events that are supported depend on the element.

The value for the syntax is a simple domain-specific language of the form:

eventName:targetId[.methodName[(arg1=value, arg2=value)]]

See the table below for descriptions of each part of the syntax.

Syntax Required? Description
eventName yes This is the name of the event that an element exposes.
targetId yes This is the DOM id for the element, or a predefined special target you'd like to execute an action on in response to the event. In the following example, the targetId is the DOM id of the amp-lightbox target, photo-slides. 
<amp-lightbox id="photo-slides"></amp-lightbox>
<button on="tap:photo-slides">Show Images</button>
methodName no This is for elements with default actions.

This is the method that the target element (referenced by targetId) exposes and you'd like to execute when the event is triggered.

AMP has a concept of a default action that elements can implement. So when omitting the methodName AMP will execute that default method.
arg=value no Some actions, if documented, may accept arguments. The arguments are defined between parentheses in key=value notation. The accepted values are:
  • simple unquoted strings: simple-value
  • quoted strings: "string value" or 'string value'
  • boolean values: true or false
  • numbers: 11 or 1.1
  • dot-syntax reference to event data: event.someDataVariableName

Handling multiple events

You can listen to multiple events on an element by separating the events with a semicolon ;.

Example: on="submit-success:lightbox1;submit-error:lightbox2"

Multiple actions for one event

You can execute multiple actions in sequence for the same event by separating the actions with a comma ','.

Example: on="tap:target1.actionA,target2.actionB"

Globally-defined events and actions

AMP defines a tap event globally that you can listen to on any HTML element (including AMP elements).

AMP also defines the hide, show and toggleVisibility actions globally that you can trigger on any HTML element.

Element-specific events

* - all elements

Event Description
tap Fired when the element is clicked/tapped.

Input elements

Event Description Elements Data
change Fired when the value of the element is changed and committed.

Data properties mirror those in HTMLInputElement and HTMLSelectElement.

 input 
event.min
event.max
event.value
event.valueAsNumber
input[type="radio"],
input[type="checkbox"]		 event.checked
select 
event.min
event.max
event.value
input-debounced Fired when the value of the element is changed. This is similar to the standard change event, but it only fires when 300ms have passed after the value of the input has stopped changing. Elements that fire input event. Same as change event data.
input-throttled Fired when the value of the element is changed. This is similar to the standard change event, but it is throttled to firing at most once every 100ms while the value of the input is changing. Elements that fire input event. Same as change event data.

amp-carousel[type="slides"]

Event Description Data
slideChange Fired when the carousel's current slide changes. 
// Slide number.
event.index
toggleAutoplay Will, on user tap or click, toggle the autoplay status for the carousel. You can either specify the status you want by specifying it: carousel-id.toggleAutoplay(toggleOn=false) or flip the status by not specifying a value. 
optional toggle status

amp-lightbox

Event Description Data
lightboxOpen Fired when lightbox is fully visible. None
lightboxClose Fired when lightbox is fully closed. None

amp-sidebar

Event Description Data
sidebarOpen Fired when sidebar is fully opened after transition has ended. None
sidebarClose Fired when sidebar is fully closed after transition has ended. None

amp-video, amp-youtube

Event Description Data
firstPlay(low-trust) Fired the first time the video is played by the user. On autoplay videos, this is fired as soon as the user interacts with the video. This event is low-trust which means it can not trigger most actions; only low-trust actions such as amp-animation actions can be run.
timeUpdate(low-trust) Fired when the playing position of a video has changed. Frequency of the event is controlled by AMP and is currently set at 1 second intervals. This event is low-trust which means it can not trigger most actions; only low-trust actions such as amp-animation actions can be run. {time, percent}time indicates the current time in seconds, percent is a number between 0 and 1 and indicates current position as percentage of total time.

form

Event Description Data
submit Fired when the form is submitted.
submit-success Fired when the form submission response is success. 
// Response JSON.
event.response
submit-error Fired when the form submission response is an error. 
// Response JSON.
event.response
valid Fired when the form is valid.
invalid Fired when the form is invalid.

Element-specific actions

* (all elements)

Action Description
hide Hides the target element.
show Shows the target element.
toggleVisibility Toggles the visibility of the target element.
toggleClass(class=STRING, force=BOOLEAN) Toggles class of the target element. force is optional, and if defined, it ensures that class would only be added but not removed if set to true, and only removed but not added if set to false.
scrollTo(duration=INTEGER, position=STRING) Scrolls an element into view with a smooth animation. If defined, duration specifies the length of the animation in milliseconds (default is 500ms). position is optional and takes one of top, center or bottom defining where in the viewport the element will be at the end of the scroll (default is top).
focus Makes the target element gain focus. To lose focus, focus on another element (usually parent element). We strongly advise against losing focus by focusing on body/documentElement for accessibility reasons.

amp-audio

Action Description
play Plays the audio. Is a no-op if the <amp-audio> element is a descendant of <amp-story>.
pause Pauses the audio. Is a no-op if the <amp-audio> element is a descendant of <amp-story>.

amp-bodymovin-animation

Action Description
play Plays the animation.
pause Pauses the animation.
stop Stops the animation.
seekTo(time=INTEGER) Sets the currentTime of the animation to the specified value and pauses animation.
seekTo(percent=[0,1]) Uses the given percentage value to determine the currentTime of the animation to the specified value and pauses animation.

amp-carousel[type="slides"]

Action Description
goToSlide(index=INTEGER) Advances the carousel to a specified slide index.

amp-image-lightbox

Action Description
open (default) Opens the image lightbox with the source image being the one that triggered the action.

amp-lightbox

Action Description
open (default) Opens the lightbox.
close Closes the lightbox.

amp-list

Action Description
refresh Refreshes data from the src and re-renders the list.

amp-live-list

Action Description
update (default) Updates the DOM items to show updated content.

amp-selector

Action Description
selectUp(delta=INTEGER) Moves the selection up by the value of delta. The default delta is set to 1.
selectDown(delta=INTEGER) Moves the selection down by the value of delta. The default delta is set to -1.
toggle(index=INTEGER, value=BOOLEAN) Sets the selected element's selected attribute if value is 'true', otherwise removes the attribute

amp-sidebar

Action Description
open (default) Opens the sidebar.
close Closes the sidebar.
toggle Toggles the state of the sidebar.

amp-user-notification

Action Description
dismiss (default) Hides the referenced user notification element.

Video elements

The actions below are supported in the following AMP video elements: amp-video, amp-youtube, amp-3q-player, amp-brid-player, amp-dailymotion, amp-ima-video.

Action Description
play Plays the video.
pause Pauses the video.
mute Mutes the video.
unmute Unmutes the video.
fullscreen Takes the video to fullscreen.

form

Action Description
clear Clears any values in the form's inputs.
submit Submits the form.

Special targets

The following are targets provided by the AMP system that have special requirements:

Target: AMP

The AMP target is provided by the AMP runtime and implements top-level actions that apply to the whole document.

Action Description
navigateTo(url=STRING) Navigates current window to given URL. Supports standard URL substitutions.
goBack Navigates back in history.
print Opens the Print Dialog to print the current page.
optoutOfCid Opts out of Client ID generation for all scopes.
setState({foo: 'bar'})1

Requires amp-bind.

Merges an object literal into the bindable state.
pushState({foo: 'bar'})1

Requires amp-bind.

Merges an object literal into the bindable state and pushes a new entry onto browser history stack. Popping the entry will restore the previous values of variables (in this example, foo).

1When used with multiple actions, subsequent actions will wait for setState() or pushState() to complete before invocation. Only a single setState() or pushState() is allowed per event.

Target: amp-access

The amp-access target is provided by the amp-access component.

The amp-access target is special for these reasons:

  1. You can't give an arbitrary ID to this target. The target is always amp-access.
  2. The actions for amp-access are dynamic depending on the structure of the AMP Access Configuration.

See details about using the amp-access target.