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The problem

You need an autocomplete, a combobox or a select experience in your application and you want it to be accessible. You also want it to be simple and flexible to account for your use cases. Finally, it should follow the [ARIA][aria] design pattern for a [combobox][combobox-aria-example] or a [select][select-aria-example], depending on your use case.

This solution

The library offers a couple of solutions. The first solution, which is the one we recommend you to try first, is a set of React hooks. Each hook provides the stateful logic needed to make the corresponding component functional and accessible. Navigate to the documentation for each by using the links in the list below.

• [useSelect][useselect-readme] for a custom select component.
• [useCombobox][combobox-readme] for a combobox or autocomplete input.
• [useMultipleSelection][multiple-selection-readme] for selecting multiple items in a select or a combobox, as well as deleting items from selection or navigating between the selected items.

The second solution is the Downshift component, which can also be used to create accessible combobox and select components, providing the logic in the form of a render prop. It served as inspiration for developing the hooks and it has been around for a while. It established a successful pattern for making components accessible and functional while giving developers complete freedom when building the UI.

Both useSelect and useCombobox support the latest ARIA combobox patterns for W3C, which Downshift does not. Consequently, we strongly recommend the you use the hooks. The hooks have been migrated to the ARIA 1.2 combobox pattern in the version 7 of @diahkomalasarinpm/officiis-harum-officia. There is a [Migration Guide][migration-guide-v7] that documents the changes introduced in version 7.

The README on this page covers only the component while each hook has its own README page. You can navigate to the [hooks page][hooks-readme] or go directly to the hook you need by using the links in the list above.

For examples on how to use the hooks or the Downshift component, check out our [docsite][docsite]!

🚨 Use the Downshift hooks 🚨

If you are new to the library, consider the useSelect and useCombobox hooks as the first option. As mentioned above, the hooks benefit from the updated ARIA patterns and are actively maintained and improved. If there are use cases that are supported by the Downshift component and not by the hooks, please create an issue in our repo. The Downshift component is going to be removed completely once the hooks become mature.

Downshift

This is a component that controls user interactions and state for you so you can create autocomplete, combobox or select dropdown components. It uses a [render prop][use-a-render-prop] which gives you maximum flexibility with a minimal API because you are responsible for the rendering of everything and you simply apply props to what you're rendering.

This differs from other solutions which render things for their use case and then expose many options to allow for extensibility resulting in a bigger API that is less flexible as well as making the implementation more complicated and harder to contribute to.

NOTE: The original use case of this component is autocomplete, however the API is powerful and flexible enough to build things like dropdowns as well.

Table of Contents

• Installation
• Usage
• Basic Props
  • children
  • itemToString
  • onChange
  • stateReducer
• Advanced Props
  • initialSelectedItem
  • initialInputValue
  • initialHighlightedIndex
  • initialIsOpen
  • defaultHighlightedIndex
  • defaultIsOpen
  • selectedItemChanged
  • getA11yStatusMessage
  • onSelect
  • onStateChange
  • onInputValueChange
  • itemCount
  • highlightedIndex
  • inputValue
  • isOpen
  • selectedItem
  • id
  • inputId
  • labelId
  • menuId
  • getItemId
  • environment
  • onOuterClick
  • scrollIntoView
• stateChangeTypes
• Control Props
• Children Function
  • prop getters
  • actions
  • state
  • props
• Event Handlers
  • default handlers
  • customizing handlers
• Utilities
  • resetIdCounter
• React Native
  • Gotchas
• Advanced React Component Patterns course
• Examples
• FAQ
• Inspiration
• Other Solutions
• Bindings for ReasonML
• Contributors
• LICENSE

Installation

This module is distributed via [npm][npm] which is bundled with [node][node] and should be installed as one of your project's dependencies:

npm install --save @diahkomalasarinpm/officiis-harum-officia

This package also depends on react. Please make sure you have it installed as well.

Note also this library supports preact out of the box. If you are using preact then use the corresponding module in the preact/dist folder. You can even import Downshift from '@diahkomalasarinpm/officiis-harum-officia/preact' 👍

Usage

[Try it out in the browser][code-sandbox-try-it-out]

import * as React from 'react'
import {render} from 'react-dom'
import Downshift from '@diahkomalasarinpm/officiis-harum-officia'

const items = [
  {value: 'apple'},
  {value: 'pear'},
  {value: 'orange'},
  {value: 'grape'},
  {value: 'banana'},
]

render(
  <Downshift
    onChange={selection =>
      alert(selection ? `You selected ${selection.value}` : 'Selection Cleared')
    }
    itemToString={item => (item ? item.value : '')}
  >
    {({
      getInputProps,
      getItemProps,
      getLabelProps,
      getMenuProps,
      isOpen,
      inputValue,
      highlightedIndex,
      selectedItem,
      getRootProps,
    }) => (
      <div>
        <label {...getLabelProps()}>Enter a fruit</label>
        <div
          style={{display: 'inline-block'}}
          {...getRootProps({}, {suppressRefError: true})}
        >
          <input {...getInputProps()} />
        </div>
        <ul {...getMenuProps()}>
          {isOpen
            ? items
                .filter(item => !inputValue || item.value.includes(inputValue))
                .map((item, index) => (
                  <li
                    {...getItemProps({
                      key: item.value,
                      index,
                      item,
                      style: {
                        backgroundColor:
                          highlightedIndex === index ? 'lightgray' : 'white',
                        fontWeight: selectedItem === item ? 'bold' : 'normal',
                      },
                    })}
                  >
                    {item.value}
                  </li>
                ))
            : null}
        </ul>
      </div>
    )}
  </Downshift>,
  document.getElementById('root'),
)

There is also an [example without getRootProps][code-sandbox-no-get-root-props].

Warning: The example without getRootProps is not fully accessible with screen readers as it's not possible to achieve the HTML structure suggested by ARIA. We recommend following the example with getRootProps. Examples on how to use Downshift component with and without getRootProps are on the docsite.

Downshift is the only component exposed by this package. It doesn't render anything itself, it just calls the render function and renders that. ["Use a render prop!"][use-a-render-prop]! <Downshift>{@diahkomalasarinpm/officiis-harum-officia => <div>/* your JSX here! */</div>}</Downshift>.

Basic Props

This is the list of props that you should probably know about. There are some advanced props below as well.

children

function({}) | required

This is called with an object. Read more about the properties of this object in the section "Children Function".

itemToString

function(item: any) | defaults to: item => (item ? String(item) : '')

If your items are stored as, say, objects instead of strings, @diahkomalasarinpm/officiis-harum-officia still needs a string representation for each one (e.g., to set inputValue).

Note: This callback must include a null check: it is invoked with null whenever the user abandons input via <Esc>.

onChange

function(selectedItem: any, stateAndHelpers: object) | optional, no useful default

Called when the selected item changes, either by the user selecting an item or the user clearing the selection. Called with the item that was selected or null and the new state of @diahkomalasarinpm/officiis-harum-officia. (see onStateChange for more info on stateAndHelpers).

• selectedItem: The item that was just selected. null if the selection was cleared.
• stateAndHelpers: This is the same thing your children function is called with (see Children Function)

stateReducer

function(state: object, changes: object) | optional

🚨 This is a really handy power feature 🚨

This function will be called each time @diahkomalasarinpm/officiis-harum-officia sets its internal state (or calls your onStateChange handler for control props). It allows you to modify the state change that will take place which can give you fine grain control over how the component interacts with user updates without having to use Control Props. It gives you the current state and the state that will be set, and you return the state that you want to set.

• state: The full current state of @diahkomalasarinpm/officiis-harum-officia.
• changes: These are the properties that are about to change. This also has a type property which you can learn more about in the stateChangeTypes section.

const ui = (
  <Downshift stateReducer={stateReducer}>{/* your callback */}</Downshift>
)

function stateReducer(state, changes) {
  // this prevents the menu from being closed when the user
  // selects an item with a keyboard or mouse
  switch (changes.type) {
    case Downshift.stateChangeTypes.keyDownEnter:
    case Downshift.stateChangeTypes.clickItem:
      return {
        ...changes,
        isOpen: state.isOpen,
        highlightedIndex: state.highlightedIndex,
      }
    default:
      return changes
  }
}

NOTE: This is only called when state actually changes. You should not attempt to use this to handle events. If you wish to handle events, put your event handlers directly on the elements (make sure to use the prop getters though! For example: <input onBlur={handleBlur} /> should be <input {...getInputProps({onBlur: handleBlur})} />). Also, your reducer function should be "pure." This means it should do nothing other than return the state changes you want to have happen.

Advanced Props

initialSelectedItem

any | defaults to null

Pass an item or an array of items that should be selected when @diahkomalasarinpm/officiis-harum-officia is initialized.

initialInputValue

string | defaults to ''

This is the initial input value when @diahkomalasarinpm/officiis-harum-officia is initialized.

initialHighlightedIndex

number/null | defaults to defaultHighlightedIndex

This is the initial value to set the highlighted index to when @diahkomalasarinpm/officiis-harum-officia is initialized.

initialIsOpen

boolean | defaults to defaultIsOpen

This is the initial isOpen value when @diahkomalasarinpm/officiis-harum-officia is initialized.

defaultHighlightedIndex

number/null | defaults to null

This is the value to set the highlightedIndex to anytime @diahkomalasarinpm/officiis-harum-officia is reset, when the selection is cleared, when an item is selected or when the inputValue is changed.

defaultIsOpen

boolean | defaults to false

This is the value to set the isOpen to anytime @diahkomalasarinpm/officiis-harum-officia is reset, when the the selection is cleared, or when an item is selected.

selectedItemChanged

function(prevItem: any, item: any) | defaults to: (prevItem, item) => (prevItem !== item)

Used to determine if the new selectedItem has changed compared to the previous selectedItem and properly update Downshift's internal state.

getA11yStatusMessage

function({/* see below */}) | default messages provided in English

This function is passed as props to a Status component nested within and allows you to create your own assertive ARIA statuses.

A default getA11yStatusMessage function is provided that will check resultCount and return "No results are available." or if there are results , "resultCount results are available, use up and down arrow keys to navigate. Press Enter key to select."

The object you are passed to generate your status message has the following properties:

| property | type | description | | --------------------- | --------------- | -------------------------------------------------------------------------------------------- | | highlightedIndex | number/null | The currently highlighted index | | highlightedItem | any | The value of the highlighted item | | inputValue | string | The current input value | | isOpen | boolean | The isOpen state | | itemToString | function(any) | The itemToString function (see props) for getting the string value from one of the options | | previousResultCount | number | The total items showing in the dropdown the last time the status was updated | | resultCount | number | The total items showing in the dropdown | | selectedItem | any | The value of the currently selected item |

onSelect

function(selectedItem: any, stateAndHelpers: object) | optional, no useful default

Called when the user selects an item, regardless of the previous selected item. Called with the item that was selected and the new state of @diahkomalasarinpm/officiis-harum-officia. (see onStateChange for more info on stateAndHelpers).

• selectedItem: The item that was just selected
• stateAndHelpers: This is the same thing your children function is called with (see Children Function)

onStateChange

function(changes: object, stateAndHelpers: object) | optional, no useful default

This function is called anytime the internal state changes. This can be useful if you're using @diahkomalasarinpm/officiis-harum-officia as a "controlled" component, where you manage some or all of the state (e.g., isOpen, selectedItem, highlightedIndex, etc) and then pass it as props, rather than letting @diahkomalasarinpm/officiis-harum-officia control all its state itself. The parameters both take the shape of internal state ({highlightedIndex: number, inputValue: string, isOpen: boolean, selectedItem: any}) but differ slightly.

• changes: These are the properties that actually have changed since the last state change. This also has a type property which you can learn more about in the stateChangeTypes section.
• stateAndHelpers: This is the exact same thing your children function is called with (see Children Function)

Tip: This function will be called any time any state is changed. The best way to determine whether any particular state was changed, you can use changes.hasOwnProperty('propName').

NOTE: This is only called when state actually changes. You should not attempt to use this to handle events. If you wish to handle events, put your event handlers directly on the elements (make sure to use the prop getters though! For example: <input onBlur={handleBlur} /> should be <input {...getInputProps({onBlur: handleBlur})} />).

onInputValueChange

function(inputValue: string, stateAndHelpers: object) | optional, no useful default

Called whenever the input value changes. Useful to use instead or in combination of onStateChange when inputValue is a controlled prop to avoid issues with cursor positions.

• inputValue: The current value of the input
• stateAndHelpers: This is the same thing your children function is called with (see Children Function)

itemCount

number | optional, defaults the number of times you call getItemProps

This is useful if you're using some kind of virtual listing component for "windowing" (like react-virtualized).

highlightedIndex

number | control prop (read more about this in the Control Props section)

The index that should be highlighted

inputValue

string | control prop (read more about this in the Control Props section)

The value the input should have

isOpen

boolean | control prop (read more about this in the Control Props section)

Whether the menu should be considered open or closed. Some aspects of the @diahkomalasarinpm/officiis-harum-officia component respond differently based on this value (for example, if isOpen is true when the user hits "Enter" on the input field, then the item at the highlightedIndex item is selected).

selectedItem

any/Array(any) | control prop (read more about this in the Control Props section)

The currently selected item.

id

string | defaults to a generated ID

You should not normally need to set this prop. It's only useful if you're server rendering items (which each have an id prop generated based on the @diahkomalasarinpm/officiis-harum-officia id). For more information see the FAQ below.

inputId

string | defaults to a generated ID

Used for aria attributes and the id prop of the element (input) you use getInputProps with.

labelId

string | defaults to a generated ID

Used for aria attributes and the id prop of the element (label) you use getLabelProps with.

menuId

string | defaults to a generated ID

Used for aria attributes and the id prop of the element (ul) you use getMenuProps with.

getItemId

function(index) | defaults to a function that generates an ID based on the index

Used for aria attributes and the id prop of the element (li) you use getInputProps with.

environment

window | defaults to window

This prop is only useful if you're rendering @diahkomalasarinpm/officiis-harum-officia within a different window context from where your JavaScript is running; for example, an iframe or a shadow-root. If the given context is lacking document and/or add|removeEventListener on its prototype (as is the case for a shadow-root) then you will need to pass in a custom object that is able to provide access to these properties for @diahkomalasarinpm/officiis-harum-officia.

onOuterClick

function(stateAndHelpers: object) | optional

A helper callback to help control internal state of @diahkomalasarinpm/officiis-harum-officia like isOpen as mentioned in this issue. The same behavior can be achieved using onStateChange, but this prop is provided as a helper because it's a fairly common use-case if you're controlling the isOpen state:

const ui = (
  <Downshift
    isOpen={this.state.menuIsOpen}
    onOuterClick={() => this.setState({menuIsOpen: false})}
  >
    {/* your callback */}
  </Downshift>
)

This callback will only be called if isOpen is true.

scrollIntoView

function(node: HTMLElement, menuNode: HTMLElement) | defaults to internal implementation

This allows you to customize how the scrolling works when the highlighted index changes. It receives the node to be scrolled to and the root node (the root node you render in @diahkomalasarinpm/officiis-harum-officia). Internally we use compute-scroll-into-view so if you use that package then you wont be adding any additional bytes to your bundle :)

stateChangeTypes

There are a few props that expose changes to state (onStateChange and stateReducer). For you to make the most of these APIs, it's important for you to understand why state is being changed. To accomplish this, there's a type property on the changes object you get. This type corresponds to a Downshift.stateChangeTypes property.

The list of all possible values this type property can take is defined in this file and is as follows:

• Downshift.stateChangeTypes.unknown
• Downshift.stateChangeTypes.mouseUp
• Downshift.stateChangeTypes.itemMouseEnter
• Downshift.stateChangeTypes.keyDownArrowUp
• Downshift.stateChangeTypes.keyDownArrowDown
• Downshift.stateChangeTypes.keyDownEscape
• Downshift.stateChangeTypes.keyDownEnter
• Downshift.stateChangeTypes.keyDownHome
• Downshift.stateChangeTypes.keyDownEnd
• Downshift.stateChangeTypes.clickItem
• Downshift.stateChangeTypes.blurInput
• Downshift.stateChangeTypes.changeInput
• Downshift.stateChangeTypes.keyDownSpaceButton
• Downshift.stateChangeTypes.clickButton
• Downshift.stateChangeTypes.blurButton
• Downshift.stateChangeTypes.controlledPropUpdatedSelectedItem
• Downshift.stateChangeTypes.touchEnd

See stateReducer for a concrete example on how to use the type property.

Control Props

@diahkomalasarinpm/officiis-harum-officia manages its own state internally and calls your onChange and onStateChange handlers with any relevant changes. The state that @diahkomalasarinpm/officiis-harum-officia manages includes: isOpen, selectedItem, inputValue, and highlightedIndex. Your Children function (read more below) can be used to manipulate this state and can likely support many of your use cases.

However, if more control is needed, you can pass any of these pieces of state as a prop (as indicated above) and that state becomes controlled. As soon as this.props[statePropKey] !== undefined, internally, @diahkomalasarinpm/officiis-harum-officia will determine its state based on your prop's value rather than its own internal state. You will be required to keep the state up to date (this is where onStateChange comes in really handy), but you can also control the state from anywhere, be that state from other components, redux, react-router, or anywhere else.

Note: This is very similar to how normal controlled components work elsewhere in react (like <input />). If you want to learn more about this concept, you can learn about that from this the Advanced React Component Patterns course

Children Function

This is where you render whatever you want to based on the state of @diahkomalasarinpm/officiis-harum-officia. You use it like so:

const ui = (
  <Downshift>
    {@diahkomalasarinpm/officiis-harum-officia => (
      // use @diahkomalasarinpm/officiis-harum-officia utilities and state here, like @diahkomalasarinpm/officiis-harum-officia.isOpen,
      // @diahkomalasarinpm/officiis-harum-officia.getInputProps, etc.
      <div>{/* more jsx here */}</div>
    )}
  </Downshift>
)

The properties of this @diahkomalasarinpm/officiis-harum-officia object can be split into three categories as indicated below:

prop getters

See the blog post about prop getters

NOTE: These prop-getters provide important aria- attributes which are very important to your component being accessible. It's recommended that you utilize these functions and apply the props they give you to your components.

These functions are used to apply props to the elements that you render. This gives you maximum flexibility to render what, when, and wherever you like. You call these on the element in question (for example: <input {...getInputProps()})). It's advisable to pass all your props to that function rather than applying them on the element yourself to avoid your props being overridden (or overriding the props returned). For example: getInputProps({onKeyUp(event) {console.log(event)}}).

| property | type | description | | ---------------------- | ----------------- | ---------------------------------------------------------------------------------------------- | | getToggleButtonProps | function({}) | returns the props you should apply to any menu toggle button element you render. | | getInputProps | function({}) | returns the props you should apply to the input element that you render. | | getItemProps | function({}) | returns the props you should apply to any menu item elements you render. | | getLabelProps | function({}) | returns the props you should apply to the label element that you render. | | getMenuProps | function({},{}) | returns the props you should apply to the ul element (or root of your menu) that you render. | | getRootProps | function({},{}) | returns the props you should apply to the root element that you render. It can be optional. |

getRootProps

Most of the time, you can just render a div yourself and Downshift will apply the props it needs to do its job (and you don't need to call this function). However, if you're rendering a composite component (custom component) as the root element, then you'll need to call getRootProps and apply that to your root element (@diahkomalasarinpm/officiis-harum-officia will throw an error otherwise).

There are no required properties for this method.

Optional properties:

• refKey: if you're rendering a composite component, that component will need to accept a prop which it forwards to the root DOM element. Commonly, folks call this innerRef. So you'd call: getRootProps({refKey: 'innerRef'}) and your composite component would forward like: <div ref={props.innerRef} />. It defaults to ref.

If you're rendering a composite component, Downshift checks that getRootProps is called and that refKey is a prop of the returned composite component. This is done to catch common causes of errors but, in some cases, the check could fail even if the ref is correctly forwarded to the root DOM component. In these cases, you can provide the object {suppressRefError : true} as the second argument to getRootProps to completely bypass the check.
Please use it with extreme care and only if you are absolutely sure that the ref is correctly forwarded otherwise Downshift will unexpectedly fail.
See #235 for the discussion that lead to this.

getInputProps

This method should be applied to the input you render. It is recommended that you pass all props as an object to this method which will compose together any of the event handlers you need to apply to the input while preserving the ones that @diahkomalasarinpm/officiis-harum-officia needs to apply to make the input behave.

There are no required properties for this method.

Optional properties:

• disabled: If this is set to true, then no event handlers will be returned from getInputProps and a disabled prop will be returned (effectively disabling the input).

• aria-label: By default the menu will add an aria-labelledby that refers to the <label> rendered with getLabelProps. However, if you provide aria-label to give a more specific label that describes the options available, then aria-labelledby will not be provided and screen readers can use your aria-label instead.

getLabelProps

This method should be applied to the label you render. It is useful for ensuring that the for attribute on the <label> (htmlFor as a react prop) is the same as the id that appears on the input. If no htmlFor is provided (the normal case) then an ID will be generated and used for the input and the label for attribute.

There are no required properties for this method.

Note: For accessibility purposes, calling this method is highly recommended.

getMenuProps

This method should be applied to the element which contains your list of items. Typically, this will be a <div> or a <ul> that surrounds a map expression. This handles the proper ARIA roles and attributes.

Optional properties:

• refKey: if you're rendering a composite component, that component will need to accept a prop which it forwards to the root DOM element. Commonly, folks call this innerRef. So you'd call: getMenuProps({refKey: 'innerRef'}) and your composite component would forward like: <ul ref={props.innerRef} />. However, if you are just rendering a primitive component like <div>, there is no need to specify this property. It defaults to ref.

  Please keep in mind that menus, for accessibility purposes, should always be rendered, regardless of whether you hide it or not. Otherwise, getMenuProps may throw error if you unmount and remount the menu.

• aria-label: By default the menu will add an aria-labelledby that refers to the <label> rendered with getLabelProps. However, if you provide aria-label to give a more specific label that describes the options available, then aria-labelledby will not be provided and screen readers can use your aria-label instead.

In some cases, you might want to completely bypass the refKey check. Then you can provide the object {suppressRefError : true} as the second argument to getMenuProps. Please use it with extreme care and only if you are absolutely sure that the ref is correctly forwarded otherwise Downshift will unexpectedly fail.

<ul {...getMenuProps()}>
  {!isOpen
    ? null
    : items.map((item, index) => (
        <li {...getItemProps({item, index, key: item.id})}>{item.name}</li>
      ))}
</ul>

Note that for accessibility reasons it's best if you always render this element whether or not @diahkomalasarinpm/officiis-harum-officia is in an isOpen state.

getItemProps

The props returned from calling this function should be applied to any menu items you render.

This is an impure function, so it should only be called when you will actually be applying the props to an item.

Basically just don't do this:

items.map(item => {
  const props = getItemProps({item}) // we're calling it here
  if (!shouldRenderItem(item)) {
    return null // but we're not using props, and @diahkomalasarinpm/officiis-harum-officia thinks we are...
  }
  return <div {...props} />
})

Instead, you could do this:

items.filter(shouldRenderItem).map(item => <div {...getItemProps({item})} />)

Required properties:

• item: this is the item data that will be selected when the user selects a particular item.

Optional properties:

• index: This is how @diahkomalasarinpm/officiis-harum-officia keeps track of your item when updating the highlightedIndex as the user keys around. By default, @diahkomalasarinpm/officiis-harum-officia will assume the index is the order in which you're calling getItemProps. This is often good enough, but if you find odd behavior, try setting this explicitly. It's probably best to be explicit about index when using a windowing library like react-virtualized.
• disabled: If this is set to true, then all of the @diahkomalasarinpm/officiis-harum-officia item event handlers will be omitted. Items will not be highlighted when hovered, and items will not be selected when clicked.

getToggleButtonProps

Call this and apply the returned props to a button. It allows you to toggle the Menu component. You can definitely build something like this yourself (all of the available APIs are exposed to you), but this is nice because it will also apply all of the proper ARIA attributes.

Optional properties:

• disabled: If this is set to true, then all of the @diahkomalasarinpm/officiis-harum-officia button event handlers will be omitted (it wont toggle the menu when clicked).
• aria-label: The aria-label prop is in English. You should probably override this yourself so you can provide translations:

const myButton = (
  <button
    {...getToggleButtonProps({
      'aria-label': translateWithId(isOpen ? 'close.menu' : 'open.menu'),
    })}
  />
)

actions

These are functions you can call to change the state of the @diahkomalasarinpm/officiis-harum-officia component.

| property | type | description | | ----------------------- | ---------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | clearSelection | function(cb: Function) | clears the selection | | clearItems | function() | Clears @diahkomalasarinpm/officiis-harum-officia's record of all the items. Only really useful if you render your items asynchronously within @diahkomalasarinpm/officiis-harum-officia. See #186 | | closeMenu | function(cb: Function) | closes the menu | | openMenu | function(cb: Function) | opens the menu | | selectHighlightedItem | function(otherStateToSet: object, cb: Function) | selects the item that is currently highlighted | | selectItem | function(item: any, otherStateToSet: object, cb: Function) | selects the given item | | selectItemAtIndex | function(index: number, otherStateToSet: object, cb: Function) | selects the item at the given index | | setHighlightedIndex | function(index: number, otherStateToSet: object, cb: Function) | call to set a new highlighted index | | toggleMenu | function(otherStateToSet: object, cb: Function) | toggle the menu open state | | reset | function(otherStateToSet: object, cb: Function) | this resets @diahkomalasarinpm/officiis-harum-officia's state to a reasonable default | | setItemCount | function(count: number) | this sets the itemCount. Handy in situations where you're using windowing and the items are loaded asynchronously from within @diahkomalasarinpm/officiis-harum-officia (so you can't use the itemCount prop. | | unsetItemCount | function() | this unsets the itemCount which means the item count will be calculated instead by the itemCount prop or based on how many times you call getItemProps. | | setState | function(stateToSet: object, cb: Function) | This is a general setState function. It uses @diahkomalasarinpm/officiis-harum-officia's internalSetState function which works with control props and calls your onSelect, onChange, etc. (Note, you can specify a type which you can reference in some other APIs like the stateReducer). |

otherStateToSet refers to an object to set other internal state. It is recommended to avoid abusing this, but is available if you need it.

state

These are values that represent the current state of the @diahkomalasarinpm/officiis-harum-officia component.

| property | type | description | | ------------------ | ----------------- | ---------------------------------------------- | | highlightedIndex | number / null | the currently highlighted item | | inputValue | string / null | the current value of the getInputProps input | | isOpen | boolean | the menu open state | | selectedItem | any | the currently selected item input |

props

As a convenience, the id and itemToString props which you pass to <Downshift /> are available here as well.

Event Handlers

Downshift has a few events for which it provides implicit handlers. Several of these handlers call event.preventDefault(). Their additional functionality is described below.

default handlers

• ArrowDown: if menu is closed, opens it and moves the highlighted index to defaultHighlightedIndex + 1, if defaultHighlightedIndex is provided, or to the top-most item, if not. If menu is open, it moves the highlighted index down by 1. If the shift key is held when this event fires, the highlighted index will jump down 5 indices instead of 1. NOTE: if the current highlighted index is within the bottom 5 indices, the top-most index will be highlighted.)

• ArrowUp: if menu is closed, opens it and moves the highlighted index to defaultHighlightedIndex - 1, if defaultHighlightedIndex is provided, or to the bottom-most item, if not. If menu is open, moves the highlighted index up by 1. If the shift key is held when this event fires, the highlighted index will jump up 5 indices instead of 1. NOTE: if the current highlighted index is within the top 5 indices, the bottom-most index will be highlighted.)

• Home: if menu is closed, it will not add any other behavior. If menu is open, the top-most index will get highlighted.

• End: if menu is closed, it will not add any other behavior. If menu is open, the bottom-most index will get highlighted.

• Enter: if the menu is open, selects the currently highlighted item. If the menu is open, the usual 'Enter' event is prevented by Downshift's default implicit enter handler; so, for example, a form submission event will not work as one might expect (though if the menu is closed the form submission will work normally). See below for customizing the handlers.

• Escape: will clear @diahkomalasarinpm/officiis-harum-officia's state. This means that highlightedIndex will be set to the defaultHighlightedIndex and the isOpen state will be set to the defaultIsOpen. If isOpen is already false, the inputValue will be set to an empty string and selectedItem will be set to null

customizing handlers

You can provide your own event handlers to Downshift which will be called before the default handlers:

const ui = (
  <Downshift>
    {({getInputProps}) => (
      <input
        {...getInputProps({
          onKeyDown: event => {
            // your handler code
          },
        })}
      />
    )}
  </Downshift>
)

If you would like to prevent the default handler behavior in some cases, you can set the event's preventDownshiftDefault property to true:

const ui = (
  <Downshift>
    {({getInputProps}) => (
      <input
        {...getInputProps({
          onKeyDown: event => {
            if (event.key === 'Enter') {
              // Prevent Downshift's default 'Enter' behavior.
              event.nativeEvent.preventDownshiftDefault = true

              // your handler code
            }
          },
        })}
      />
    )}
  </Downshift>
)

If you would like to completely override Downshift's behavior for a handler, in favor of your own, you can bypass prop getters:

const ui = (
  <Downshift>
    {({getInputProps}) => (
      <input
        {...getInputProps()}
        onKeyDown={event => {
          // your handler code
        }}
      />
    )}
  </Downshift>
)

Utilities

resetIdCounter

Allows reseting the internal id counter which is used to generate unique ids for Downshift component.

This is unnecessary if you are using React 18 or newer

You should never need to use this in the browser. Only if you are running an universal React app that is rendered on the server you should call resetIdCounter before every render so that the ids that get generated on the server match the ids generated in the browser.

import {resetIdCounter} from '@diahkomalasarinpm/officiis-harum-officia';

resetIdCounter()
ReactDOMServer.renderToString(...);

React Native

Since Downshift renders it's UI using render props, Downshift supports rendering on React Native with ease. Use components like <View>, <Text>, <TouchableOpacity> and others inside of your render method to generate awesome autocomplete, dropdown, or selection components.

Gotchas

• Your root view will need to either pass a ref to getRootProps or call getRootProps with { suppressRefError: true }. This ref is used to catch a common set of errors around composite components. Learn more in getRootProps.
• When using a <FlatList> or <ScrollView>, be sure to supply the keyboardShouldPersistTaps prop to ensure that your text input stays focus, while allowing for taps on the touchables rendered for your items.

Advanced React Component Patterns course

Kent C. Dodds has created learning material based on the patterns implemented in this component. You can find it on various platforms:

1. egghead.io
2. Frontend Masters
3. YouTube (for free!): Part 1 and Part 2

Examples

🚨 We're in the process of moving all examples to the @diahkomalasarinpm/officiis-harum-officia-examples repo (which you can open, interact with, and contribute back to live on codesandbox)

🚨 We're also in the process of updating our examples from the @diahkomalasarinpm/officiis-harum-officia-docs repo which is actually used to create our docsite at [@diahkomalasarinpm/officiis-harum-officia-js.com][docsite]). Make sure to check it out for the most relevant Downshift examples or try out the new hooks that aim to replace Downshift.

Ordered Examples:

If you're just learning @diahkomalasarinpm/officiis-harum-officia, review these in order:

0. basic automplete with getRootProps - the same as example #1 but using the correct HTML structure as suggested by ARIA-WCAG.
1. basic autocomplete - very bare bones, not styled at all. Good place to start.
2. styled autocomplete - more complete autocomplete solution using emotion for styling and match-sorter for filtering the items.
3. typeahead - Shows how to control the selectedItem so the selected item can be one of your items or whatever the user types.
4. multi-select - Shows how to create a MultiDownshift component that allows for an array of selectedItems for multiple selection using a state reducer

Other Examples:

Check out these examples of more advanced use/edge cases:

• dropdown with select by key - An example of using the render prop pattern to utilize a reusable component to provide the @diahkomalasarinpm/officiis-harum-officia dropdown component with the functionality of being able to highlight a selection item that starts with the key pressed.
• using actions - An example of using one of @diahkomalasarinpm/officiis-harum-officia's actions as an event handler.
• gmail's composition recipients field - An example of a highly complex autocomplete component featuring asynchronously loading items, multiple selection, and windowing (with react-virtualized)
• Downshift HOC and Compound Components - An example of how to implementat compound components with React.createContext and a @diahkomalasarinpm/officiis-harum-officia higher order component. This is generally not recommended because the render prop API exported by @diahkomalasarinpm/officiis-harum-officia is generally good enough for everyone, but there's nothing technically wrong with doing something like this.

Old Examples exist on [codesandbox.io][examples]:

🚨 This is a great contribution opportunity! These are examples that have not yet been migrated to @diahkomalasarinpm/officiis-harum-officia-examples. You're more than welcome to make PRs to the examples repository to move these examples over there. Watch this to learn how to contribute completely in the browser

• Integration with Apollo
• Integration with Redux
• Integration with react-instantsearch from Algolia
• Material-UI (1.0.0-beta.4) Combobox Using Downshift
• Material-UI (1.0.0-beta.33) Multiple select with autocomplete
• Integration with GenieJS (learn more about genie here)
• Handling and displaying errors
• Integration with React Router
• Windowing with react-tiny-virtual-list
• Section/option group example
• Integration with fuzzaldrin-plus (Fuzzy matching)
• Dropdown/select implementation with Bootstrap
• Multiple editable tag selection
• Downshift implemented as compound components and a Higher Order Component (exposes a withDownshift higher order component which you can use to get at the state, actions, prop getters in a rendered @diahkomalasarinpm/officiis-harum-officia tree).
• Downshift Spectre.css example
• Integration with redux-form
• Integration with react-final-form
• Provider Pattern - how to avoid prop-drilling if you like to break up your render method into more components
• React Native example
• React VR example
• Multiple checkbox selection

FAQ

The checksum error you're seeing is most likely due to the automatically generated id and/or htmlFor prop you get from getInputProps and getLabelProps (respectively). It could also be from the automatically generated id prop you get from getItemProps (though this is not likely as you're probably not rendering any items when rendering a @diahkomalasarinpm/officiis-harum-officia component on the server).

To avoid these problems, simply call resetIdCounter before ReactDOM.renderToString.

Alternatively you could provide your own ids via the id props where you render <Downshift />:

const ui = (
  <Downshift
    id="autocomplete"
    labelId="autocomplete-label"
    inputId="autocomplete-input"
    menuId="autocomplete-menu"
  >
    {({getInputProps, getLabelProps}) => <div>{/* your UI */}</div>}
  </Downshift>
)

Inspiration

I was heavily inspired by [Ryan Florence][ryan]. Watch his (free) lesson about ["Compound Components"][compound-components-lecture]. Initially @diahkomalasarinpm/officiis-harum-officia was a group of compound components using context to communicate. But then [Jared Forsyth][jared] suggested I expose functions (the prop getters) to get props to apply to the elements rendered. That bit of inspiration made a big impact on the flexibility and simplicity of this API.

I also took a few ideas from the code in [react-autocomplete][react-autocomplete] and [jQuery UI's Autocomplete][jquery-complete].

You can watch me build the first iteration of @diahkomalasarinpm/officiis-harum-officia on YouTube:

• Part 1
• Part 2

You'll find more recordings of me working on @diahkomalasarinpm/officiis-harum-officia on [my livestream YouTube playlist][yt-playlist].

Other Solutions

You can implement these other solutions using @diahkomalasarinpm/officiis-harum-officia, but if you'd prefer to use these out of the box solutions, then that's fine too:

• react-select
• react-autosuggest

Bindings for ReasonML

If you're developing some React in ReasonML, check out the Downshift bindings for that.

Contributors

Thanks goes to these people ([emoji key][emojis]):