Combobox

A combobox is an input widget with an associated popup that enables users to select a value from a collection of possible values.

Features

• Support for selecting multiple values
• Support for disabled options
• Support for custom user input values
• Support for mouse, touch, and keyboard interactions
• Keyboard support for opening the combo box list box using the arrow keys, including automatically focusing the first or last item accordingly

Installation

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

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

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

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

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

This command will install the framework agnostic combobox logic and the reactive utilities for your framework of choice.

Anatomy

To set up the combobox 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 combobox package into your project

import * as combobox from "@zag-js/combobox"

The combobox package exports these functions:

• machine — The state machine logic for the combobox widget.
• connect — The function that translates the machine's state to JSX attributes and event handlers.
• collection - The function that creates a collection interface from an array of items.

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

import * as combobox from "@zag-js/combobox"
import { useMachine, normalizeProps } from "@zag-js/react"

const comboboxData = [
  { label: "Zambia", code: "ZA" },
  { label: "Benin", code: "BN" },
  //...
]

export function Combobox() {
  const [options, setOptions] = useState(comboboxData)

  const collection = combobox.collection({
    items: options,
    itemToValue: (item) => item.code,
    itemToString: (item) => item.label,
  })

  const [state, send] = useMachine(
    combobox.machine({
      id: useId(),
      collection,
      onOpenChange() {
        setOptions(comboboxData)
      },
      onInputValueChange({ value }) {
        const filtered = comboboxData.filter((item) =>
          item.label.toLowerCase().includes(value.toLowerCase()),
        )
        setOptions(filtered.length > 0 ? filtered : comboboxData)
      },
    }),
    {
      context: { collection },
    },
  )

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

  return (
    <div>
      <div {...api.rootProps}>
        <label {...api.labelProps}>Select country</label>
        <div {...api.controlProps}>
          <input {...api.inputProps} />
          <button {...api.triggerProps}>▼</button>
        </div>
      </div>
      <div {...api.positionerProps}>
        {options.length > 0 && (
          <ul {...api.contentProps}>
            {options.map((item) => (
              <li key={item.code} {...api.getItemProps({ item })}>
                {item.label}
              </li>
            ))}
          </ul>
        )}
      </div>
    </div>
  )
}

import * as combobox from "@zag-js/combobox"
import { normalizeProps, useMachine } from "@zag-js/solid"
import { createMemo, createSignal, createUniqueId, For, Show } from "solid-js"

const comboboxData = [
  { label: "Zambia", code: "ZA" },
  { label: "Benin", code: "BN" },
  //...
]

export function Combobox() {
  const [options, setOptions] = createSignal(comboboxData)

  const collection = createMemo(() =>
    combobox.collection({
      items: options(),
      itemToValue: (item) => item.code,
      itemToString: (item) => item.label,
    }),
  )

  const [state, send] = useMachine(
    combobox.machine({
      id: createUniqueId(),
      collection: collection(),
      onOpenChange() {
        setOptions(comboboxData)
      },
      onInputValueChange({ value }) {
        const filtered = comboboxData.filter((item) =>
          item.label.toLowerCase().includes(value.toLowerCase()),
        )
        setOptions(filtered.length > 0 ? filtered : comboboxData)
      },
    }),
  )

  const api = createMemo(() => combobox.connect(state, send, normalizeProps))

  return (
    <div>
      <div {...api().rootProps}>
        <label {...api().labelProps}>Select country</label>
        <div {...api().controlProps}>
          <input {...api().inputProps} />
          <button {...api().triggerProps}>▼</button>
        </div>
      </div>
      <div {...api().positionerProps}>
        <Show when={options().length > 0}>
          <ul {...api().contentProps}>
            <For each={options()}>
              {(item) => (
                <li {...api().getItemProps({ item })}>{item.label}</li>
              )}
            </For>
          </ul>
        </Show>
      </div>
    </div>
  )
}

import * as combobox from "@zag-js/combobox"
import { normalizeProps, useMachine } from "@zag-js/vue"
import { computed, defineComponent, ref } from "vue"

const comboboxData = [
  { label: "Zambia", code: "ZA" },
  { label: "Benin", code: "BN" },
  //...
]

export default defineComponent({
  name: "Combobox",
  setup() {
    const options = ref(comboboxData)

    const collectionRef = computed(() =>
      combobox.collection({
        items: options.value,
        itemToString: (item) => item.label,
        itemToValue: (item) => item.code,
      }),
    )

    const [state, send] = useMachine(
      combobox.machine({
        id: "v1",
        collection: collectionRef.value,
        onOpenChange() {
          options.value = comboboxData
        },
        onInputValueChange({ value }) {
          const filtered = comboboxData.filter((item) =>
            item.label.toLowerCase().includes(value.toLowerCase()),
          )
          options.value = filtered.length > 0 ? filtered : comboboxData
        },
      }),
      {
        context: computed(() => ({
          collection: collectionRef.value,
        })),
      },
    )

    const apiRef = computed(() =>
      combobox.connect(state.value, send, normalizeProps),
    )

    return () => {
      const api = apiRef.value

      return (
        <div>
          <div {...api.rootProps}>
            <label {...api.labelProps}>Select country</label>

            <div {...api.controlProps}>
              <input {...api.inputProps} />
              <button {...api.triggerProps}>▼</button>
            </div>
          </div>

          <div {...api.positionerProps}>
            {options.value.length > 0 && (
              <ul {...api.contentProps}>
                {options.value.map((item) => (
                  <li key={item.code} {...api.getItemProps({ item })}>
                    {item.label}
                  </li>
                ))}
              </ul>
            )}
          </div>
        </div>
      )
    }
  },
})

<script setup>
  import * as combobox from "@zag-js/combobox"
  import { normalizeProps, useMachine } from "@zag-js/vue"
  import { computed, ref } from "vue"

  const comboboxData = [
    { label: "Zambia", code: "ZA" },
    { label: "Benin", code: "BN" },
    //...
  ]

  const options = ref(comboboxData)

  const collectionRef = computed(() =>
    combobox.collection({
      items: options.value,
      itemToValue: (item) => item.code,
      itemToString: (item) => item.label,
    }),
  )

  const [state, send] = useMachine(
    combobox.machine({
      id: "1",
      collection: collectionRef.value,
      onOpenChange() {
        options.value = comboboxData
      },
      onInputValueChange({ value }) {
        const filtered = comboboxData.filter((item) =>
          item.label.toLowerCase().includes(value.toLowerCase()),
        )
        options.value = filtered.length > 0 ? filtered : comboboxData
      },
    }),
    {
      context: computed(() => ({
        collection: collectionRef.value,
      })),
    },
  )

  const api = computed(() =>
    combobox.connect(state.value, send, normalizeProps),
  )
</script>

<template>
  <div v-bind="api.rootProps">
    <label v-bind="api.labelProps">Select country</label>

    <div v-bind="api.controlProps">
      <input v-bind="api.inputProps" />
      <button v-bind="api.triggerProps">▼</button>
    </div>
  </div>
  <div v-bind="api.positionerProps">
    <ul v-if="options.length > 0" v-bind="api.contentProps">
      <li
        v-for="item in options"
        :key="item.code"
        v-bind="api.getItemProps({ item })"
      >
        {{ item.label }}
      </li>
    </ul>
  </div>
</template>

Setting the initial value

To set the initial value of the combobox, pass the value property to the machine's context.

The value property must be an array of strings. If selecting a single value, pass an array with a single string.

const collection = combobox.collection({
  items: [
    { label: "Nigeria", value: "ng" },
    { label: "Ghana", value: "gh" },
    { label: "Kenya", value: "ke" },
    //...
  ],
})

const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    collection,
    value: ["ng"],
  }),
)

Selecting multiple values

To allow selecting multiple values, set the multiple property in the machine's context to true.

const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    collection,
    multiple: true,
  }),
)

Using a custom object format

By default, the combobox collection expects an array of items with label and value properties. To use a custom object format, pass the itemToString and itemToValue properties to the collection function.

• itemToString — A function that returns the string representation of an item. Used to compare items when filtering.
• itemToValue — A function that returns the unique value of an item.
• itemToDisabled — A function that returns the disabled state of an item.

const collection = combobox.collection({
  // custom object format
  items: [
    { id: 1, fruit: "Banana", available: true, quantity: 10 },
    { id: 2, fruit: "Apple", available: false, quantity: 5 },
    { id: 3, fruit: "Orange", available: true, quantity: 3 },
    //...
  ],
  // convert item to string
  itemToString(item) {
    return item.fruit
  },
  // convert item to value
  itemToValue(item) {
    return item.id
  },
  // convert item to disabled state
  itemToDisabled(item) {
    return !item.available || item.quantity === 0
  },
})

// use the collection
const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    collection,
  }),
)

Rendering the selected values outside the combobox

By default, the selected values of a combobox are displayed in the input element, when selecting multiple items, it is a better UX to render the selected value outside the combobox.

To achieve this you need to:

• Set the selectionBehavior to clear, which clears the input value when an item is selected.
• Set the multiple property to true to allow selecting multiple values.
• Render the selected values outside the combobox.

const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    collection,
    selectionBehavior: "clear",
    multiple: true,
  }),
)

Disabling the combobox

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

const [state, send] = useMachine(
  combobox.machine({
    disabled: true,
  }),
)

Disabling an option

To make a combobox option disabled, pass the isItemDisabled property to the collection function.

const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    collection: combobox.collection({
      items: countries,
      isItemDisabled(item) {
        return item.disabled
      },
    }),
  }),
)

Close on select

This behaviour ensures that the menu is closed when an option is selected and is true by default. It's only concerned with when an option is selected with pointer or enter key. To disable the behaviour, set the closeOnSelect property in the machine's context to false.

const [state, send] = useMachine(
  combobox.machine({
    closeOnSelect: false,
  }),
)

Making the combobox readonly

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

const [state, send] = useMachine(
  combobox.machine({
    readOnly: true,
  }),
)

Listening for highlight changes

When an option is highlighted with the pointer or keyboard, use the onHighlightChange property to listen for this change and do something with it.

const [state, send] = useMachine(
  combobox.machine({
    id: useId(),
    onHighlightChange(details) {
      // details => { value: string | null; item: CollectionItem | null }
      console.log(details)
    },
  }),
)

Listening for value changes

When an item is selected, use onValueChange property to listen for this change and do something with it.

const [state, send] = useMachine(
  combobox.machine({
    onValueChange(details) {
      // details => { value: string[]; items: CollectionItem[] }
      console.log(details)
    },
  }),
)

Usage within forms

The combobox works when placed within a form and the form is submitted. We achieve this by:

• ensuring we emit the input event as the value changes.
• adding a name attribute to the input so the value can be accessed in the FormData.

To get this feature working you need to pass a name option to the context.

const [state, send] = useMachine(
  combobox.machine({
    name: "countries",
  }),
)

Allowing custom values

By default, the combobox only allows selecting values from the collection. To allow custom values, set the allowCustomValue property in the machine's context to true.

const [state, send] = useMachine(
  combobox.machine({
    allowCustomValue: true,
  }),
)

Styling guide

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

Open and closed state

When the combobox is open or closed, the data-state attribute is added to the content,control, input and control parts.

[data-part="control"][data-state="open|closed"] {
  /* styles for control open or state */
}

[data-part="input"][data-state="open|closed"] {
  /* styles for control open or state */
}

[data-part="trigger"][data-state="open|closed"] {
  /* styles for control open or state */
}

[data-part="content"][data-state="open|closed"] {
  /* styles for control open or state */
}

Focused State

When the combobox is focused, the data-focus attribute is added to the control and label parts.

[data-part="control"][data-focus] {
  /* styles for control focus state */
}

[data-part="label"][data-focus] {
  /* styles for label focus state */
}

Disabled State

When the combobox is disabled, the data-disabled attribute is added to the label, control, trigger and option parts.

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

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

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

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

Invalid State

When the combobox is invalid, the data-invalid attribute is added to the root, label, control and input parts.

[data-part="root"][data-invalid] {
  /* styles for root invalid state */
}

[data-part="label"][data-invalid] {
  /* styles for label invalid state */
}

[data-part="control"][data-invalid] {
  /* styles for control invalid state */
}

[data-part="input"][data-invalid] {
  /* styles for input invalid state */
}

Selected State

When a combobox item is selected, the data-selected attribute is added to the item part.

[data-part="item"][data-state="checked|unchecked"] {
  /* styles for item selected state */
}

Highlighted State

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

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

Methods and Properties

Machine Context

The combobox machine exposes the following context properties:

• idsPartial<{ root: string; label: string; control: string; input: string; content: string; trigger: string; clearTrigger: string; item(id: string, index?: number): string; positioner: string; itemGroup(id: string | number): string; itemGroupLabel(id: string | number): string; }>The ids of the elements in the combobox. Useful for composition.
• inputValuestringThe current value of the combobox's input
• namestringThe `name` attribute of the combobox's input. Useful for form submission
• formstringThe associate form of the combobox.
• disabledbooleanWhether the combobox is disabled
• readOnlybooleanWhether the combobox is readonly. This puts the combobox in a "non-editable" mode but the user can still interact with it
• invalidbooleanWhether the combobox is required
• placeholderstringThe placeholder text of the combobox's input
• highlightedValuestringThe active item's id. Used to set the `aria-activedescendant` attribute
• valuestring[]The keys of the selected items
• inputBehavior"autohighlight" | "autocomplete" | "none"Defines the auto-completion behavior of the combobox. - `autohighlight`: The first focused item is highlighted as the user types - `autocomplete`: Navigating the listbox with the arrow keys selects the item and the input is updated
• selectionBehavior"clear" | "replace" | "preserve"The behavior of the combobox input when an item is selected - `replace`: The selected item string is set as the input value - `clear`: The input value is cleared - `preserve`: The input value is preserved
• selectOnBlurbooleanWhether to select the higlighted item on interaction outside the combobox
• autoFocusbooleanWhether to autofocus the input on mount
• openOnClickbooleanWhether to open the combobox popup on initial click on the input
• allowCustomValuebooleanWhether to allow custom values or free values in the input
• loopbooleanWhether to loop the keyboard navigation through the items
• positioningPositioningOptionsThe positioning options to dynamically position the menu
• onInputValueChange(details: InputValueChangeDetails) => voidFunction called when the input's value changes
• onValueChange(details: ValueChangeDetails<T>) => voidFunction called when a new item is selected
• onHighlightChange(details: HighlightChangeDetails<T>) => voidFunction called when an item is highlighted using the pointer or keyboard navigation.
• onOpenChange(details: OpenChangeDetails) => voidFunction called when the popup is opened
• translationsIntlTranslationsSpecifies the localized strings that identifies the accessibility elements and their states
• collectionCollection<any>The collection of items
• multiplebooleanWhether to allow multiple selection
• closeOnSelectbooleanWhether to close the combobox when an item is selected.
• 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.
• onPointerDownOutside(event: PointerDownOutsideEvent) => voidFunction called when the pointer is pressed down outside the component
• onFocusOutside(event: FocusOutsideEvent) => voidFunction called when the focus is moved outside the component
• onInteractOutside(event: InteractOutsideEvent) => voidFunction called when an interaction happens outside the component

Machine API

The combobox api exposes the following methods:

• isFocusedbooleanWhether the combobox is focused
• isOpenbooleanWhether the combobox is open
• isInputValueEmptybooleanWhether the combobox input value is empty
• inputValuestringThe value of the combobox input
• highlightedValuestringThe value of the highlighted item
• highlightedItemVThe highlighted item
• highlightValue(value: string) => voidThe value of the combobox input
• selectedItemsV[]The selected items
• hasSelectedItemsbooleanWhether there's a selected item
• valuestring[]The selected item keys
• valueAsStringstringThe string representation of the selected items
• selectValue(value: string) => voidFunction to select a value
• setValue(value: string[]) => voidFunction to set the value of the combobox
• clearValue(value?: string) => voidFunction to clear the value of the combobox
• focus() => voidFunction to focus on the combobox input
• setInputValue(value: string) => voidFunction to set the input value of the combobox
• getItemState(props: ItemProps) => ItemStateReturns the state of a combobox item
• open() => voidFunction to open the combobox
• close() => voidFunction to close the combobox
• setCollection(collection: Collection<V>) => voidFunction to set the collection of items
• reposition(options: Partial<PositioningOptions>) => voidFunction to set the positioning options