Rating Group

Rating group allows a user to assign rating to an item within a product.

Features

• Support for syncing disabled state of with fieldset element
• Support for form reset events

Installation

To use the rating group machine in your project, run the following command in your command line:

npm install @zag-js/rating-group @zag-js/react
# or
yarn add @zag-js/rating-group @zag-js/react

npm install @zag-js/rating-group @zag-js/solid
# or
yarn add @zag-js/rating-group @zag-js/solid

npm install @zag-js/rating-group @zag-js/vue
# or
yarn add @zag-js/rating-group @zag-js/vue

npm install @zag-js/rating-group @zag-js/svelte
# or
yarn add @zag-js/rating-group @zag-js/svelte

Anatomy

To set up the rating correctly, you'll need to understand its anatomy and how we name its parts.

Each part includes a data-part attribute to help identify them in the DOM.

Usage

First, import the rating package into your project

import * as rating from "@zag-js/rating-group"

The rating package exports two key functions:

• machine — The state machine logic for the rating widget.
• connect — The function that translates the machine's state to JSX attributes and event handlers.

You'll also need to provide a unique id to the useMachine hook. This is used to ensure that every part has a unique identifier.

Next, import the required hooks and functions for your framework and use the rating machine in your project 🔥

import * as rating from "@zag-js/rating-group"
import { useMachine, normalizeProps } from "@zag-js/react"
import { HalfStar, Star } from "./icons"

function Rating() {
  const service = useMachine(rating.machine, { id: "1" })

  const api = rating.connect(service, normalizeProps)

  return (
    <div {...api.getRootProps()}>
      <label {...api.getLabelProps()}>Rate:</label>
      <div {...api.getControlProps()}>
        {api.items.map((index) => {
          const state = api.getItemState({ index })
          return (
            <span key={index} {...api.getItemProps({ index })}>
              {state.half ? <HalfStar /> : <Star />}
            </span>
          )
        })}
      </div>
      <input {...api.getHiddenInputProps()} />
    </div>
  )
}

import * as rating from "@zag-js/rating-group"
import { useMachine, normalizeProps } from "@zag-js/solid"
import { createMemo, createUniqueId } from "solid-js"
import { HalfStar, Star } from "./icons"

function Rating() {
  const service = useMachine(rating.machine, { id: createUniqueId() })

  const api = createMemo(() => rating.connect(service, normalizeProps))

  return (
    <div {...api().getRootProps()}>
      <label {...api().getLabelProps()}>Rate:</label>
      <div {...api().getControlProps()}>
        {api().items.map((index) => {
          const state = api().getItemState(index)
          return (
            <span key={index} {...api().getItemProps({ index })}>
              {state.half ? <HalfStar /> : <Star />}
            </span>
          )
        })}
      </div>
      <input {...api().getHiddenInputProps()} />
    </div>
  )
}

<script setup>
  import * as rating from "@zag-js/rating-group"
  import { normalizeProps, useMachine } from "@zag-js/vue"
  import { computed } from "vue"
  import { HalfStar, Star } from "./icons"

  const service = useMachine(rating.machine, { id: "1" })

  const api = computed(() => rating.connect(service, normalizeProps))
</script>

<template>
  <div v-bind="api.getRootProps()">
    <label v-bind="api.getLabelProps()">Rate:</label>
    <div v-bind="api.getControlProps()">
      <span
        v-for="index in api.items"
        :key="index"
        v-bind="api.getItemProps({ index })"
      >
        <HalfStar v-if="api.getItemState({ index }).half" />
        <Star v-else />
      </span>
    </div>
    <input v-bind="api.getHiddenInputProps()" />
  </div>
</template>

<script lang="ts">
  import * as rating from "@zag-js/rating-group"
  import { normalizeProps, useMachine } from "@zag-js/svelte"

  const id = $props.id()
  const service = useMachine(rating.machine, {
    id,
    defaultValue: 2.5,
  })
  const api = $derived(rating.connect(service, normalizeProps))
</script>

<div {...api.getRootProps()}>
  <label {...api.getLabelProps()}>Rate:</label>
  <div {...api.getControlProps()}>
    {#each api.items as index}
      {@const snapshot = api.getItemState({ index })}
      <span {...api.getItemProps({ index })}>
        {#if snapshot.half}
          {@render HalfStar()}
        {:else}
          {@render Star()}
        {/if}
      </span>
    {/each}
  </div>
  <input {...api.getHiddenInputProps()} data-testid="hidden-input" />
</div>

Disabling the rating group

To make rating disabled, set the context's disabled property to true

const service = useMachine(rating.machine, {
  disabled: true,
})

Making the rating readonly

To make rating readonly, set the context's readOnly property to true

const service = useMachine(rating.machine, {
  readOnly: true,
})

Setting the initial value

Use the defaultValue property to set the rating's initial value.

const service = useMachine(rating.machine, {
  defaultValue: 2.5,
})

Listening for changes

When the rating value changes, the onValueChange callback is invoked.

const service = useMachine(rating.machine, {
  onValueChange({ value }) {
    console.log("rating value is:", value)
    // '1' | '2.5' | '4'
  },
})

Usage within forms

To use rating within forms, use the exposed inputProps from the connect function and ensure you pass name value to the machine's context. It will render a hidden input and ensure the value changes get propagated to the form correctly.

const service = useMachine(rating.machine, {
  name: "rating",
})

Styling guide

Earlier, we mentioned that each rating part has a data-part attribute added to them to select and style them in the DOM.

Disabled State

When the rating is disabled, the data-disabled attribute is added to the rating, control and label parts.

[data-part="rating"][data-disabled] {
  /* styles for rating disabled state */
}

[data-part="label"][data-disabled] {
  /* styles for rating control disabled state */
}

[data-part="input"][data-disabled] {
  /* styles for rating label disabled state */
}

Checked State

When the rating is checked, the data-checked attribute is added to the rating part.

[data-part="rating"][data-checked] {
  /* styles for rating checked state */
}

Readonly State

When the rating is readonly, the data-readonly attribute is added to the rating part.

[data-part="rating"][data-readonly] {
  /* styles for rating readonly state */
}

Highlighted

When a rating is highlighted, the data-highlighted attribute is added to the rating part.

[data-part="rating"][data-highlighted] {
  /* styles for highlighted rating */
}

Half rating

When a rating is half, the data-half attribute is added to the rating part.

[data-part="rating"][data-half] {
  /* styles for half rating */
}

Methods and Properties

Machine Context

The rating group machine exposes the following context properties:

• idsPartial<{ root: string; label: string; hiddenInput: string; control: string; item: (id: string) => string; }>The ids of the elements in the rating. Useful for composition.
• translationsIntlTranslationsSpecifies the localized strings that identifies the accessibility elements and their states
• countnumberThe total number of ratings.
• namestringThe name attribute of the rating element (used in forms).
• formstringThe associate form of the underlying input element.
• valuenumberThe controlled value of the rating
• defaultValuenumberThe initial value of the rating when rendered. Use when you don't need to control the value of the rating.
• readOnlybooleanWhether the rating is readonly.
• disabledbooleanWhether the rating is disabled.
• requiredbooleanWhether the rating is required.
• allowHalfbooleanWhether to allow half stars.
• autoFocusbooleanWhether to autofocus the rating.
• onValueChange(details: ValueChangeDetails) => voidFunction to be called when the rating value changes.
• onHoverChange(details: HoverChangeDetails) => voidFunction to be called when the rating value is hovered.
• dir"ltr" | "rtl"The document's text/writing direction.
• idstringThe unique identifier of the machine.
• getRootNode() => ShadowRoot | Node | DocumentA root node to correctly resolve document in custom environments. E.x.: Iframes, Electron.

Machine API

The rating group api exposes the following methods:

• setValue(value: number) => voidSets the value of the rating group
• clearValueVoidFunctionClears the value of the rating group
• hoveringbooleanWhether the rating group is being hovered
• valuenumberThe current value of the rating group
• hoveredValuenumberThe value of the currently hovered rating
• countnumberThe total number of ratings
• itemsnumber[]The array of rating values. Returns an array of numbers from 1 to the max value.
• getItemState(props: ItemProps) => ItemStateReturns the state of a rating item

Data Attributes

Accessibility

Keyboard Interactions

• ArrowRight
  Moves focus to the next star, increasing the rating value based on the `allowHalf` property.
• ArrowLeft
  Moves focus to the previous star, decreasing the rating value based on the `allowHalf` property.
• Enter
  Selects the focused star in the rating group.