downshift

See
the intro blog post
and
Episode 79 of the Full Stack Radio podcast

The problem

You need an autocomplete/dropdown/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.

This solution

This library provides its users two main sets of solutions: the Downshift
component and a set of hooks. The component is still the main part of the
library, providing autocomplete/combobox logic as a render prop. The hooks are
newer and are going to be the way forward to provide accessibility logic to
widgets. Right now we support useSelect for <select> components and
useCombobox for combobox/autocomplete.

Since useCombobox and <Downshift /> aim to provide accessibility to the same
kind of widget, we suggest trying the new useCombobox and if you feel that
<Downshift /> still covers your use case better then use that instead. Both of
them are actively maintained but we are cool kids from the future and prefer to
share React logic via hooks.

The README on this page is only for the component while each hook has its own
README file, check below. But they are similar in many concepts so you can
always switch between them in order to find information.

Downshift component

This is a component that controls user interactions and state for you so you can
create autocomplete, dropdown, select, etc. components. It uses 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.

The Hooks API

In the effort to provide out of the box solutions for each dropdown variation, a
set of React Hooks are being added as part of Downshift. Each hook will handle a
specific dropdown variation and be named accordingly: useSelect,
useCombobox, useMultipleSelection etc.

You can check the progress in the hooks page and contribute! If
you want to create a custom <select> or combobox autocomplete dropdown and
want it to be functional and accessible, jump directly to the already
implemented useSelect and useCombobox.
For more examples of how to use the hooks check out our
docsite!

Bundle size concerns

Adding the hooks into this repo increased the bundle size considerably
throughout its existence. However, since we create the bundle with Rollup and
export both <Downshift> and the hooks as modules, you should be able to have
the library treeshaked (pruned) and given only the code you need. Since version
3.4.8 BundlePhobia marked Downshift as both tree-shakeable and
side-effect free here.

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 which is bundled with node and
should be installed as one of your project's dependencies:

npm install --save downshift

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 'downshift/preact' ?

Usage

Try it out in the browser

import React from 'react'
import {render} from 'react-dom'
import Downshift from 'downshift'

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'),
)

The previous example without getRootProps is
here.

Warning: The example without getRootProps is not fully accessible with
screen readers as it's not possible to achieve a correct HTML structure for
the combobox. 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!"!
<Downshift>{downshift => <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: i => (i == null ? '' : String(i))

Used to determine the string value for the selected item (which is used to
compute the inputValue).

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 downshift. (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 downshift 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 downshift.
• 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 downshift is
initialized.

initialInputValue

string, defaults to ''

This is the initial input value when downshift is initialized.

initialHighlightedIndex

number/null, defaults to defaultHighlightedIndex

This is the initial value to set the highlighted index to when downshift is
initialized.

initialIsOpen

boolean, defaults to defaultIsOpen

This is the initial isOpen value when downshift is initialized.

defaultHighlightedIndex

number/null, defaults to null

This is the value to set the highlightedIndex to anytime downshift 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 downshift 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." or if there are results but no item is
highlighted, "resultCount results are available, use up and down arrow keys to
navigate." If an item is highlighted it will run itemToString(highlightedItem)
and display the value of the highlightedItem.

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

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 downshift. (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 downshift 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 downshift 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
downshift 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 downshift
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 downshift 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 downshift.

onOuterClick

function(stateAndHelpers: object), optional

A helper callback to help control internal state of downshift 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 downshift). 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.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

downshift manages its own state internally and calls your onChange and
onStateChange handlers with any relevant changes. The state that downshift
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, downshift 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 downshift.
You use it like so:

const ui = (
  <Downshift>
    {downshift => (
      // use downshift utilities and state here, like downshift.isOpen,
      // downshift.getInputProps, etc.
      <div>{/* more jsx here */}</div>
    )}
  </Downshift>
)

The properties of this downshift 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)}}).

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 (downshift 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 downshift 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).

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 downshift 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 downshift 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 downshift keeps track of your item when updating the
  highlightedIndex as the user keys around. By default, downshift 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 downshift 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 downshift 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 downshift component.

recommended to avoid abusing this, but is available if you need it.

state

These are values that represent the current state of the downshift component.

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 downshift's state. This means that highlightedIndex
  will be set to the defaultHighlightedIndex, the inputValue will be set to
  empty string, selectedItem will be set to null, and the isOpen state
  will be set to the defaultIsOpen.

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.

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 'downshift';

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
downshift-examples repo
(which you can open, interact with, and contribute back to live on
codesandbox)

Ordered Examples:

If you're just learning downshift, review these in order:

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 downshift 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 downshift'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 downshift higher order component. This is
  generally not recommended because the render prop API exported by downshift is
  generally good enough for everyone, but there's nothing technically wrong with
  doing something like this.

Old Examples exist on codesandbox.io:

? This is a great contribution opportunity! These are examples that have not
yet been migrated to
downshift-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 downshift 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 downshift 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. Watch his (free) lesson about
"Compound Components". Initially downshift was a
group of compound components using context to communicate. But then Jared
Forsyth 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 and jQuery UI's
Autocomplete.

You can watch me build the first iteration of downshift on YouTube:

• Part 1
• Part 2

You'll find more recordings of me working on downshift on my livestream
YouTube playlist.

Other Solutions

You can implement these other solutions using downshift, but if you'd prefer
to use these out of the box solutions, then that's fine too:

• react-select
• react-autocomplete

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):

This project follows the all-contributors specification.
Contributions of any kind welcome!

LICENSE

MIT