View Source Phoenix.LiveView.JS (Phoenix LiveView v0.20.10)

Provides 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.

Client Utility Commands

The following utilities are included:

  • add_class - Add classes to elements, with optional transitions
  • remove_class - Remove classes from elements, with optional transitions
  • toggle_class - Sets or removes classes from elements, with optional transitions
  • set_attribute - Set an attribute on elements
  • remove_attribute - Remove an attribute from elements
  • toggle_attribute - Sets or removes element attribute based on attribute presence.
  • show - Show elements, with optional transitions
  • hide - Hide elements, with optional transitions
  • toggle - Shows or hides elements based on visibility, with optional transitions
  • transition - Apply a temporary transition to elements for animations
  • dispatch - 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>
  """
end

Enhanced 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

<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>

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.

Summary

Functions

Adds classes to elements.

Dispatches an event to the DOM.

Executes JS commands located in element attributes.

Sends focus to a selector.

Sends focus to the first focusable child in selector.

Hides elements.

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.

Focuses the last pushed element.

Pushes an event to the server.

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.

Toggles element visibility.

Sets or removes element attribute based on attribute presence.

Toggles classes on an element.

Transitions elements.

Types

@opaque t()

Functions

Adds classes to elements.

  • names - The string of classes to add.

Options

  • :to - The optional DOM selector to add classes to. Defaults to the interacted element.
  • :transition - The 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 to apply the transition from :transition. Defaults 200

Examples

<div id="item">My Item</div>
<button phx-click={JS.add_class("highlight underline", to: "#item")}>
  highlight!
</button>

See add_class/1.

Link to this function

add_class(js, names, opts)

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See add_class/1.

Link to this function

dispatch(js \\ %JS{}, event)

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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 - The optional DOM selector to dispatch the event to. Defaults to the interacted element.
  • :detail - The optional detail map to dispatch along with the client event. The details will be available in the event.detail attribute for event listeners.
  • :bubbles – The boolean flag to bubble the event or not. Default true.

Examples

window.addEventListener("click", e => console.log("clicked!", e.detail))

<button phx-click={JS.dispatch("click", to: ".nav")}>Click me!</button>
Link to this function

dispatch(js, event, opts)

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See dispatch/2.

Executes JS commands located in element attributes.

  • attr - The string attribute where the JS command is specified

Options

  • :to - The optional DOM selector to fetch the attribute from. Defaults to the current element.

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 - The optional DOM selector to send focus to. Defaults to the current element.

Examples

JS.focus(to: "main")

See focus/1.

Sends focus to the first focusable child in selector.

Options

  • :to - The optional DOM selector to focus. Defaults to the current element.

Examples

JS.focus_first(to: "#modal")

See focus_first/1.

Hides elements.

Options

  • :to - The optional DOM selector to hide. Defaults to the interacted element.
  • :transition - The 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 to apply the transition from :transition. Defaults 200

During the process, the following events will be dispatched to the hidden elements:

  • When the action is triggered on the client, phx:hide-start is dispatched.
  • After the time specified by :time, phx:hide-end is 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.

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 false.

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 - The selector or component ID to push to. This value will overwrite any phx-target attribute present on the element.
  • :loading - The selector to apply the phx loading classes to.
  • :page_loading - Boolean to trigger the phx:page-loading-start and phx:page-loading-stop events for this push. Defaults to false.
  • :value - The map of values to send to the server. These values will be merged over any phx-value-* attributes that are present on the element. All keys will be treated as strings when merging.

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 - The optional DOM selector to push focus to. Defaults to the current element.

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 - The optional DOM selector to remove attributes from. Defaults to the interacted element.

Examples

<button phx-click={JS.remove_attribute("aria-expanded", to: "#dropdown")}>
  hide
</button>
Link to this function

remove_attribute(attr, opts)

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See remove_attribute/1.

Link to this function

remove_attribute(js, attr, opts)

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See remove_attribute/1.

Removes classes from elements.

  • names - The string of classes to remove.

Options

  • :to - The optional DOM selector to remove classes from. Defaults to the interacted element.
  • :transition - The 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 to apply the transition from :transition. Defaults 200

Examples

<div id="item">My Item</div>
<button phx-click={JS.remove_class("highlight underline", to: "#item")}>
  remove highlight!
</button>

See remove_class/1.

Link to this function

remove_class(js, names, opts)

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See remove_class/1.

Sets an attribute on elements.

Accepts a tuple containing the string attribute name/value pair.

Options

  • :to - The optional DOM selector to add attributes to. Defaults to the interacted element.

Examples

<button phx-click={JS.set_attribute({"aria-expanded", "true"}, to: "#dropdown")}>
  show
</button>

See set_attribute/1.

Link to this function

set_attribute(js, arg, opts)

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See set_attribute/1.

Shows elements.

Options

  • :to - The optional DOM selector to show. Defaults to the interacted element.
  • :transition - The 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 to apply the transition from :transition. Defaults 200
  • :display - The optional display value to set when showing. Defaults "block".

During the process, the following events will be dispatched to the shown elements:

  • When the action is triggered on the client, phx:show-start is dispatched.
  • After the time specified by :time, phx:show-end is 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 - The optional DOM selector to toggle. Defaults to the interacted element.
  • :in - The 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 - The 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 to apply the transition :in and :out classes. Defaults 200
  • :display - The optional display value to set when toggling in. Defaults "block".

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 between val1 and val2

Options

  • :to - The optional DOM selector to set or remove attributes from. Defaults to the interacted element.

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>
Link to this function

toggle_attribute(js, opts)

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See toggle_attribute/1.

Link to this function

toggle_attribute(js, arg, opts)

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See toggle_attribute/1.

Toggles classes on an element.

  • names - The string of classes to add.

Options

  • :to - The optional DOM selector to toggle classes to. Defaults to the interacted element.
  • :transition - The 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 to apply the transition from :transition. Defaults 200

Examples

<div id="item">My Item</div>
<button phx-click={JS.toggle_class("active", to: "#item")}>
  toggle active!
</button>
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toggle_class(js, names, opts)

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Transitions elements.

  • transition - The 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"}

Transitions are useful for temporarily adding an animation class to element(s), such as for highlighting content changes.

Options

  • :to - The optional DOM selector to apply transitions to. Defaults to the interacted element.
  • :time - The time to apply the transition from :transition. Defaults 200

Examples

<div id="item">My Item</div>
<button phx-click={JS.transition("shake", to: "#item")}>Shake!</button>
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transition(transition, opts)

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See transition/1.

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transition(js, transition, opts)

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See transition/1.