Overview

LiveViewJS user events (clicks, etc) typically trigger a server-side event which updates the state of the LiveView and re-renders the HTML. Sometimes you want to update the DOM without (or in addition to) initiating a server round trip. This is where JS Commands come in.

JS Commands support a number of client-side DOM manipulation function that can be used to update the DOM without a server round trip. These functions are:

• add_class - Add css classes to an element including optional transition classes
• remove_class - Remove css classes from an element including optional transition classes
• set_attribute - Set an attribute on an element
• remove_attribute - Remove an attribute from an element
• show - Show an element including optional transition classes
• hide - Hide an element including optional transition classes
• toggle - Toggle the visibility of an element
• dispatch - Dispatch a DOM event from an element
• transition - Apply transition classes to an element (i.e., animate it)
• push - Push an event to the LiveView server (i.e., trigger a server round trip)

JS Command Syntax

JS Commands are used in the render function of a LiveView or LiveComponent:

import { JS } from 'lieviewjs';

//... render function of a LiveView
render() {
  return html`
    <div>
      <button phx-click="${new JS().toggle({ to: "#toggle" })}">Toggle</button>
      <div id="toggle">Toggle Me</div>
    </div>
  `;
}

"Chainable" (i.e., fluent) Syntax

JS Commands are "chainable" (i.e., fluent) so you can chain multiple commands together as needed and they will be executed in the order they are called:

import { JS } from 'lieviewjs';

//... render function of a LiveView
render() {
  // hide the button then push the "increment" event to the server
  return html`
    <div>
      <button phx-click="${new JS().hide().push("increment")}">Increment</button>
    </div>
  `;
}

Example JS Commands LiveView

See packages/examples/src/liveviews/jsCommands for a working, complete set of examples of using JS Commands.

More details on each JS Command can be found in the following sections.