Composition

Event composition

Zag encourages the use of spread props to ensure we automatically attach all the event handlers and properties to elements.

Sometimes, you may want to attach your own event handlers to the elements. To do that, import the mergeProps utility provided by zag for your framework.

// 1. import mergeProps utility
import { useMachine, mergeProps } from "@zag-js/react"
import * as toggle from "@zag-js/toggle"

export function Toggle() {
  const [state, send] = useMachine(
    toggle.machine({
      id: "1",
    }),
  )
  const api = toggle.connect(state, send)

  // 2. write your custom event handlers
  const handleClick = () => {
    // do something
  }

  // 3. merge the props
  const buttonProps = mergeProps(api.buttonProps, {
    onClick: handleClick,
  })

  return (
    // 4. spread the new props
    <button {...buttonProps}>{api.isPressed ? "On" : "Off"}</button>
  )
}

Id composition

Zag depends heavily on pure DOM queries to identify elements. This means every element part needs to have a unique id.

Each time you initiate the machine with the useMachine hook, you'll need to ensure that you provide a unique id.

You can rely on framework-specific utilities to generate unique ids. React provides useId() hook and Solid.js provides a createId() function for this purpose.

/// ...                                          👇 must be unique
const [state, send] = useMachine(toggle.machine({ id: useId() }))
/// ...

Internally, Zag maps the unique id provided to each component parts needed for the widget to work.

In some cases, you might want to compose different machines together in a single component. For example, you want to use the same trigger as a popover and tooltip trigger at the same time.

To achieve this, you will need to pass custom ids to the machine's context. This will ensure that calling document.getElementById(...) within the toolip and/or popover will return the same element.

import * as tooltip from "@zag-js/tooltip"
import * as popover from "@zag-js/popover"

function Example() {
  const [tooltipState, tooltipSend] = useMachine(
    tooltip.machine({
      ids: { trigger: "id-1" },
    }),
  )
  const [popoverState, popoverSend] = useMachine(
    popover.machine({
      ids: { trigger: "id-1" },
    }),
  )
}

// render UI
return </>

In the example above, you will notice that the popover and tooltip trigger share the same id. That's how to compose machines together.

Custom window environment

Internally, we use DOM query methods like document.querySelectorAll and document.getElementById to locate elements within the machine.

In custom environments like iframe, Shadow DOM, Electron, etc., the machine might not work as expected because document may not be available.

To provide the correct reference to root node or document, you can pass getRootNode function it to the machine's context.

In shadow DOM, the root node can be derived from calling element.getRootNode() method on any element.

import * as accordion from "@zag-js/accordion"
import { useMachine, normalizeProps } from "@zag-js/react"
import Frame, { useFrame } from "react-frame-component"

const data = [
  { title: "Watercraft", content: "Sample accordion content" },
  { title: "Automobiles", content: "Sample accordion content" },
  { title: "Aircrafts", content: "Sample accordion content" },
]

function Accordion({ id }) {
  const { document } = useFrame()

  const [state, send] = useMachine(
    accordion.machine({ id, getRootNode: () => document }),
  )

  const api = accordion.connect(state, send, normalizeProps)

  return (
    <div {...api.rootProps}>
      {data.map((item, index) => (
        <div key={index} {...api.getItemProps({ value: item.title })}>
          <h3>
            <button {...api.getTriggerProps({ value: item.title })}>
              {item.title}
            </button>
          </h3>
          <div {...api.getContentProps({ value: item.title })}>
            {item.content}
          </div>
        </div>
      ))}
    </div>
  )
}

export default function App() {
  return (
    <div className="App">
      <h1>ZagJs in Iframe</h1>
      <Frame height="200px" width="100%">
        <Accordion id="2" />
      </Frame>
    </div>
  )
}

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