htmx/www/attributes/hx-trigger.md

layout	title
layout.njk	</> htmx - hx-trigger

hx-trigger

The hx-trigger attribute allows you to specify what triggers an AJAX request. A trigger value can be one of the following:

• An event name (e.g. "click" or "my-custom-event") followed by an event filter and a set of event modifiers
• A polling definition of the form every <timing declaration>
• A comma-separated list of such events

Standard Events

A standard event, such as click can be specified as the trigger like so:

<div hx-get="/clicked" hx-trigger="click">Click Me</div>

Standard Event Filters

Events can be filtered by enclosing a boolean javascript expression in square brackets after the event name. If this expression evaluates to true the event will be triggered, otherwise it will be ignored.

<div hx-get="/clicked" hx-trigger="click[ctrlKey]">Control Click Me</div>

This event will trigger if a click event is triggered with the event.ctrlKey property set to true.

Conditions can also refer to global functions or state

<div hx-get="/clicked" hx-trigger="click[checkGlobalState()]">Control Click Me</div>

And can also be combined using the standard javascript syntax

<div hx-get="/clicked" hx-trigger="click[ctrlKey&&shfitKey]">Control-Shift Click Me</div>

Note that all symbols used in the expression will be resolved first against the triggering event, and then next against the global namespace, so myEvent[foo] will first look for a property named foo on the event, then look for a global symbol with the name foo

Standard Event Modifiers

Standard events can also have modifiers that change how they behave. The modifiers are:

• once - the event will only trigger once (e.g. the first click)
• changed - the event will only change if the value of the element has changed
• delay:<timing declaration> - a delay will occur before an event triggers a request. If the event is seen again it will reset the delay.
• throttle:<timing declaration> - a throttle will occur before an event triggers a request. If the event is seen again before the delay completes it is ignored, the element will trigger at the end of the delay.

Here is an example of a search box that searches on keyup, but only if the search value has changed and the user hasn't typed anything new for 1 second:

<input name="q" 
       hx-get="/search" hx-trigger="keyup changed delay:1s"
       hx-target="#search-results"/>

The response from the /register url will be appended to the div with the id response-div.

There are two special events that are non-standard that htmx supports:

• load - triggered on load (useful for lazy-loading something)
• revealed - triggered when an element is scrolled into the viewport (also useful for lazy-loading)

Polling

By using the syntax every <timing declaration> you can have an element poll periodically:

<div hx-get="/latest_updates" hx-trigger="every 1s">
  Nothing Yet!
</div>

This example will issue a GET to the /latest_updates URL every second and swap the results into the innerHTML of this div.

Multiple Triggers

Multiple triggers can be provided, seprarated by commas. Each trigger gets its own options.

  <div hx-get="/news" hx-trigger="load, click delay:1s"></div>

This example will load /news immediate on the page load, and then again with a delay of one second after each click.

Notes

• hx-trigger is not inherited