Phoenix.LiveView.JS (Phoenix LiveView v1.1.4)
View SourceProvides commands for executing JavaScript utility operations on the client.
JS commands support a variety of utility operations for common client-side needs, such as adding or removing CSS classes, setting or removing tag attributes, showing or hiding content, and transitioning in and out with animations. While these operations can be accomplished via client-side hooks, JS commands are DOM-patch aware, so operations applied by the JS APIs will stick to elements across patches from the server.
In addition to purely client-side utilities, the JS commands include a
rich push API, for extending the default phx- binding pushes with
options to customize targets, loading states, and additional payload values.
If you need to trigger these commands via JavaScript, see JavaScript interoperability.
Client Utility Commands
The following utilities are included:
add_class- Add classes to elements, with optional transitionsremove_class- Remove classes from elements, with optional transitionstoggle_class- Sets or removes classes from elements, with optional transitionsset_attribute- Set an attribute on elementsremove_attribute- Remove an attribute from elementstoggle_attribute- Sets or removes element attribute based on attribute presence.ignore_attributes- Marks attributes as ignored, skipping them when patching the DOM.show- Show elements, with optional transitionshide- Hide elements, with optional transitionstoggle- Shows or hides elements based on visibility, with optional transitionstransition- Apply a temporary transition to elements for animationsdispatch- Dispatch a DOM event to elements
For example, the following modal component can be shown or hidden on the client without a trip to the server:
alias Phoenix.LiveView.JS
def hide_modal(js \\ %JS{}) do
js
|> JS.hide(transition: "fade-out", to: "#modal")
|> JS.hide(transition: "fade-out-scale", to: "#modal-content")
end
def modal(assigns) do
~H"""
<div id="modal" class="phx-modal" phx-remove={hide_modal()}>
<div
id="modal-content"
class="phx-modal-content"
phx-click-away={hide_modal()}
phx-window-keydown={hide_modal()}
phx-key="escape"
>
<button class="phx-modal-close" phx-click={hide_modal()}>✖</button>
<p>{@text}</p>
</div>
</div>
"""
endEnhanced push events
The push/1 command allows you to extend the built-in pushed event handling
when a phx- event is pushed to the server. For example, you may wish to
target a specific component, specify additional payload values to include
with the event, apply loading states to external elements, etc. For example,
given this basic phx-click event:
<button phx-click="inc">+</button>Imagine you need to target your current component, and apply a loading state to the parent container while the client awaits the server acknowledgement:
alias Phoenix.LiveView.JS
~H"""
<button phx-click={JS.push("inc", loading: ".thermo", target: @myself)}>+</button>
"""Push commands also compose with all other utilities. For example, to add a class when pushing:
<button phx-click={
JS.push("inc", loading: ".thermo", target: @myself)
|> JS.add_class("warmer", to: ".thermo")
}>+</button>Any phx-value-* attributes will also be included in the payload, their
values will be overwritten by values given directly to push/1. Any
phx-target attribute will also be used, and overwritten.
<button
phx-click={JS.push("inc", value: %{limit: 40})}
phx-value-room="bedroom"
phx-value-limit="this value will be 40"
phx-target={@myself}
>+</button>DOM Selectors
The client utility commands in this module all take an optional DOM selector
using the :to option.
This can be a string for a regular DOM selector such as:
JS.add_class("warmer", to: ".thermo")
JS.hide(to: "#modal")
JS.show(to: "body a:nth-child(2)")It is also possible to provide scopes to the DOM selector. The following scopes are available:
{:inner, "selector"}To target an element within the interacted element.{:closest, "selector"}To target the closest element from the interacted element upwards.
For example, if building a dropdown component, the button could use the :inner
scope:
<div phx-click={JS.show(to: {:inner, ".menu"})}>
<div>Open me</div>
<div class="menu hidden" phx-click-away={JS.hide()}>
I'm in the dropdown menu
</div>
</div>Custom JS events with JS.dispatch/1 and window.addEventListener
dispatch/1 can be used to dispatch custom JavaScript events to
elements. For example, you can use JS.dispatch("click", to: "#foo"),
to dispatch a click event to an element.
This also means you can augment your elements with custom events,
by using JavaScript's window.addEventListener and invoking them
with dispatch/1. For example, imagine you want to provide
a copy-to-clipboard functionality in your application. You can
add a custom event for it:
window.addEventListener("my_app:clipcopy", (event) => {
if ("clipboard" in navigator) {
const text = event.target.textContent;
navigator.clipboard.writeText(text);
} else {
alert("Sorry, your browser does not support clipboard copy.");
}
});Now you can have a button like this:
<button phx-click={JS.dispatch("my_app:clipcopy", to: "#element-with-text-to-copy")}>
Copy content
</button>The combination of dispatch/1 with window.addEventListener is
a powerful mechanism to increase the amount of actions you can trigger
client-side from your LiveView code.
You can also use window.addEventListener to listen to events pushed
from the server. You can learn more in our JS interoperability guide.
Composing JS commands
All the functions in this module optionally accept an existing %JS{} struct as the first argument,
allowing you to chain multiple commands, like pushing an event to the server and optimistically hiding
a modal:
<div id="modal" class="modal">
My Modal
</div>
<button phx-click={JS.push("modal-closed") |> JS.remove_class("show", to: "#modal", transition: "fade-out")}>
hide modal
</button>Note that the commands themselves are executed on the client in the order they are composed
and the client does not wait for a confirmation before executing the next command. If you chain
JS.push(...) |> JS.hide(...), since hide is a fully client-side command, it hides immediately
after pushing the event, not waiting for the server to respond.
JS commands interacting with the server are documented as such. If you chain multiple commands that interact with the server, those are also guaranteed to be executed in the order they are composed, since a LiveView can only handle one event at a time. Therefore, if you do something like
JS.push("my-event") |> JS.patch("/my-path?foo=bar")it is guaranteed that the event will be pushed first and the patch will only be handled after the first event was handled by the LiveView.
Summary
Functions
Adds classes to elements.
Combines two JS commands, appending the second to the first.
Dispatches an event to the DOM.
Executes JS commands located in an element's attribute.
See exec/1.
Sends focus to a selector.
See focus/1.
Sends focus to the first focusable child in selector.
Hides elements.
See hide/1.
Mark attributes as ignored, skipping them when patching the DOM.
Sends a navigation event to the server and updates the browser's pushState history.
Sends a patch event to the server and updates the browser's pushState history.
See patch/1.
Focuses the last pushed element.
Pushes an event to the server.
See push/1.
Pushes focus from the source element to be later popped.
Removes an attribute from elements.
Removes classes from elements.
Sets an attribute on elements.
Shows elements.
See show/1.
Toggles element visibility.
See toggle/1.
Sets or removes element attribute based on attribute presence.
Adds or removes element classes based on presence.
Transitions elements.
Types
@opaque internal()
@type t() :: %Phoenix.LiveView.JS{ops: internal()}
Functions
Adds classes to elements.
names- A string with one or more class names to add.
Options
:to- An optional DOM selector to add classes to. Defaults to the interacted element. See theDOM selectorssection for details.:transition- A string of classes to apply before adding classes or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
Examples
<div id="item">My Item</div>
<button phx-click={JS.add_class("highlight underline", to: "#item")}>
highlight!
</button>See add_class/1.
See add_class/1.
Combines two JS commands, appending the second to the first.
Dispatches an event to the DOM.
event- The string event name to dispatch.
Note: All events dispatched are of a type
CustomEvent,
with the exception of "click". For a "click", a
MouseEvent
is dispatched to properly simulate a UI click.
For emitted CustomEvent's, the event detail will contain a dispatcher,
which references the DOM node that dispatched the JS event to the target
element.
Options
:to- An optional DOM selector to dispatch the event to. Defaults to the interacted element. See theDOM selectorssection for details.:detail- An optional detail map to dispatch along with the client event. The details will be available in theevent.detailattribute for event listeners.:bubbles– A boolean flag to bubble the event or not. Defaults totrue.:blocking- A boolean flag to block the UI until the event handler callsevent.detail.done(). The done function is injected by LiveView and must be called eventually to unblock the UI. This is useful to integrate with third party JavaScript based animation libraries.
Examples
window.addEventListener("click", e => console.log("clicked!", e.detail))<button phx-click={JS.dispatch("click", to: ".nav")}>Click me!</button>See dispatch/2.
Executes JS commands located in an element's attribute.
attr- The string attribute where the JS command is specified
Options
:to- An optional DOM selector to fetch the attribute from. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
<div id="modal" phx-remove={JS.hide("#modal")}>...</div>
<button phx-click={JS.exec("phx-remove", to: "#modal")}>close</button>See exec/1.
See exec/1.
Sends focus to a selector.
Options
:to- An optional DOM selector to send focus to. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
JS.focus(to: "main")See focus/1.
Sends focus to the first focusable child in selector.
Options
:to- An optional DOM selector to focus. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
JS.focus_first(to: "#modal")See focus_first/1.
Hides elements.
Note: Only targets elements that are visible, meaning they have a height and/or width greater than zero.
Options
:to- An optional DOM selector to hide. Defaults to the interacted element. See theDOM selectorssection for details.:transition- A string of classes to apply before hiding or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-100", "opacity-0"}:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
During the process, the following events will be dispatched to the hidden elements:
- When the action is triggered on the client,
phx:hide-startis dispatched. - After the time specified by
:time,phx:hide-endis dispatched.
Examples
<div id="item">My Item</div>
<button phx-click={JS.hide(to: "#item")}>
hide!
</button>
<button phx-click={JS.hide(to: "#item", transition: "fade-out-scale")}>
hide fancy!
</button>See hide/1.
Mark attributes as ignored, skipping them when patching the DOM.
Accepts a single attribute name or a list of attribute names.
An asterisk * can be used as a wildcard.
Once set, the given attributes will not be patched across LiveView updates. This includes attributes that are removed by the server.
If you need to "unmark" an attribute, you need to call ignore_attributes/1 again
with an updated list of attributes.
This is mostly useful in combination with the phx-mounted binding, for example:
<dialog phx-mounted={JS.ignore_attributes("open")}>
...
</dialog>Options
:to- An optional DOM selector to select the target element. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
JS.ignore_attributes(["open", "data-*"], to: "#my-dialog")Sends a patch event to the server and updates the browser's pushState history.
Options
:replace- Whether to replace the browser's pushState history. Defaults tofalse.
Examples
JS.patch("/my-path")See patch/1.
See patch/1.
Focuses the last pushed element.
Examples
JS.pop_focus()Pushes an event to the server.
event- The string event name to push.
Options
:target- A selector or component ID to push to. This value will overwrite anyphx-targetattribute present on the element.:loading- A selector to apply the phx loading classes to, such asphx-click-loadingin case the event was triggered byphx-click. The element will be locked from server updates until the push is acknowledged by the server.:page_loading- Boolean to trigger the phx:page-loading-start and phx:page-loading-stop events for this push. Defaults tofalse.:value- A map of values to send to the server. These values will be merged over anyphx-value-*attributes that are present on the element. All keys will be treated as strings when merging. When used on a form event likephx-changeorphx-submit, the precedence isJS.push value > phx-value-* > input value.
Examples
<button phx-click={JS.push("clicked")}>click me!</button>
<button phx-click={JS.push("clicked", value: %{id: @id})}>click me!</button>
<button phx-click={JS.push("clicked", page_loading: true)}>click me!</button>See push/1.
See push/1.
Pushes focus from the source element to be later popped.
Options
:to- An optional DOM selector to push focus to. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
JS.push_focus()
JS.push_focus(to: "#my-button")See push_focus/1.
Removes an attribute from elements.
attr- The string attribute name to remove.
Options
:to- An optional DOM selector to remove attributes from. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
<button phx-click={JS.remove_attribute("aria-expanded", to: "#dropdown")}>
hide
</button>See remove_attribute/1.
See remove_attribute/1.
Removes classes from elements.
names- A string with one or more class names to remove.
Options
:to- An optional DOM selector to remove classes from. Defaults to the interacted element. See theDOM selectorssection for details.:transition- A string of classes to apply before removing classes or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
Examples
<div id="item">My Item</div>
<button phx-click={JS.remove_class("highlight underline", to: "#item")}>
remove highlight!
</button>See remove_class/1.
See remove_class/1.
Sets an attribute on elements.
Accepts a tuple containing the string attribute name/value pair.
Options
:to- An optional DOM selector to add attributes to. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
<button phx-click={JS.set_attribute({"aria-expanded", "true"}, to: "#dropdown")}>
show
</button>See set_attribute/1.
See set_attribute/1.
Shows elements.
Note: Only targets elements that are hidden, meaning they have a height and/or width equal to zero.
Options
:to- An optional DOM selector to show. Defaults to the interacted element. See theDOM selectorssection for details.:transition- A string of classes to apply before showing or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.:display- An optional display value to set when showing. Defaults to"block".
During the process, the following events will be dispatched to the shown elements:
- When the action is triggered on the client,
phx:show-startis dispatched. - After the time specified by
:time,phx:show-endis dispatched.
Examples
<div id="item">My Item</div>
<button phx-click={JS.show(to: "#item")}>
show!
</button>
<button phx-click={JS.show(to: "#item", transition: "fade-in-scale")}>
show fancy!
</button>See show/1.
Toggles element visibility.
Options
:to- An optional DOM selector to toggle. Defaults to the interacted element. See theDOM selectorssection for details.:in- A string of classes to apply when toggling in, or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}:out- A string of classes to apply when toggling out, or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-100", "opacity-0"}:time- The time in milliseconds to apply the transition:inand:outclasses. Defaults to 200.:display- An optional display value to set when toggling in. Defaults to"block".:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
When the toggle is complete on the client, a phx:show-start or phx:hide-start, and
phx:show-end or phx:hide-end event will be dispatched to the toggled elements.
Examples
<div id="item">My Item</div>
<button phx-click={JS.toggle(to: "#item")}>
toggle item!
</button>
<button phx-click={JS.toggle(to: "#item", in: "fade-in-scale", out: "fade-out-scale")}>
toggle fancy!
</button>See toggle/1.
Sets or removes element attribute based on attribute presence.
Accepts a two or three-element tuple:
{attr, val}- Sets the attribute to the given value or removes it{attr, val1, val2}- Toggles the attribute betweenval1andval2
Options
:to- An optional DOM selector to set or remove attributes from. Defaults to the interacted element. See theDOM selectorssection for details.
Examples
<button phx-click={JS.toggle_attribute({"aria-expanded", "true", "false"}, to: "#dropdown")}>
toggle
</button>
<button phx-click={JS.toggle_attribute({"open", "true"}, to: "#dialog")}>
toggle
</button>See toggle_attribute/1.
See toggle_attribute/1.
Adds or removes element classes based on presence.
names- A string with one or more class names to toggle.
Options
:to- An optional DOM selector to target. Defaults to the interacted element. See theDOM selectorssection for details.:transition- A string of classes to apply before adding classes or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
Examples
<div id="item">My Item</div>
<button phx-click={JS.toggle_class("active", to: "#item")}>
toggle active!
</button>Transitions elements.
transition- A string of classes to apply during the transition or a 3-tuple containing the transition class, the class to apply to start the transition, and the ending transition class, such as:{"ease-out duration-300", "opacity-0", "opacity-100"}
Transitions are useful for temporarily adding an animation class to elements, such as for highlighting content changes.
Options
:to- An optional DOM selector to apply transitions to. Defaults to the interacted element. See theDOM selectorssection for details.:time- The time in milliseconds to apply the transition from:transition. Defaults to 200.:blocking- A boolean flag to block the UI during the transition. Defaultstrue.
Examples
<div id="item">My Item</div>
<button phx-click={JS.transition("shake", to: "#item")}>Shake!</button>
<div phx-mounted={JS.transition({"ease-out duration-300", "opacity-0", "opacity-100"}, time: 300)}>
duration-300 milliseconds matches time: 300 milliseconds
</div>See transition/1.
See transition/1.