downshift 🏎

Primitives to build simple, flexible, WAI-ARIA compliant React autocomplete/dropdown/select/combobox components

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 is a collection of primitive components that you can compose together to create an autocomplete component which you can reuse in your application. It's based on ideas from the talk "Compound Components" which effectively gives you maximum flexibility with a minimal API because you are responsible for the rendering of the autocomplete components.

This differs from other solutions which render things for their use case and then expose many options to allow for extensibility causing an API that is less easy to use and 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.

Installation

This component is currently under development and is not yet released...

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@beta

This package also depends on react and prop-types. Please make sure you have those installed as well.

Usage

Things are still in flux a little bit (looking for feedback).

import Autocomplete from 'downshift'

function BasicAutocomplete({items, onChange}) {
  return (
    <Autocomplete onChange={onChange}>
      {({
        getInputProps,
        getItemProps,
        isOpen,
        inputValue,
        selectedValue,
        highlightedIndex
      }) => (
        <div>
          <input {...getInputProps({placeholder: 'Favorite color ?'})} />
          {isOpen ? (
            <div style={{border: '1px solid #ccc'}}>
              {items
                .filter(
                  i =>
                    !inputValue ||
                    i.toLowerCase().includes(inputValue.toLowerCase()),
                )
                .map((item, index) => (
                  <div
                    {...getItemProps({value: item, index})}
                    key={item}
                    style={{
                      backgroundColor:
                        highlightedIndex === index ? 'gray' : 'white',
                      fontWeight: selectedValue === item ? 'bold' : 'normal',
                    }
                  >
                    {item}
                  </div>
                ))}
            </div>
          ) : null}
        </div>
      )}
    </Autocomplete>
  )
}

function App() {
  return (
    <BasicAutocomplete
      items={['apple', 'orange', 'carrot']}
      onChange={({selectedValue}) => console.log(selectedValue)}
    />
  )
}

Available components and relevant props:

Autocomplete

This is the only component. It doesn't render anything itself, it just calls the child function and renders that. Wrap everything in this.

getValue

function(item: any) | defaults to an identity function (i => String(i))

Used to determine the value for the selected item.

defaultValue

any/Array(any) | defaults to null or an empty array ([]) if the multiple prop is true

Pass an item or an array of items that should be selected by default.

defaultHighlightedIndex

number/null | defaults to null

This is the initial index to highlight when the autocomplete first opens.

multiple

boolean | defaults to false

Specifies that multiple items can be selected at once. This means that when an item is selected it will be added to the value array rather than replacing the existing value.

getA11yStatusMessage

function({ resultCount, highlightedItem, getValue}) | 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 getValue(highlightedItem) and display the value of the highlightedItem.

onChange

function({selectedValue, previousValue}) | required

Called when the user selects an item

onStateChange

function({highlightedIndex, inputValue, isOpen, selectedValue}) | not required, 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, selectedValue, highlightedIndex, etc) and then pass it as props, rather than letting downshift control all its state itself.

highlightedIndex

number | state prop (read more below)

The index that should be highlighted

inputValue

string | state prop (read more below)

The value the input should have

isOpen

boolean | state prop (read more below)

Whether the menu should be considered open or closed. Some aspects of the autocomplete 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).

`selectedValue`

any/Array(any) | state prop (read more below)

The currently selected value.

children

function({}) | required

This is called with an object with the properties listed below:

property	type	description
`getRootProps`	`function({})`	returns the props you should apply to the root element that you render. It can be optional. Read more below
`getInputProps`	`function({})`	returns the props you should apply to the `input` element that you render. Read more below
`getLabelProps`	`function({})`	returns the props you should apply to the `label` element that you render. Read more below
`getItemProps`	`function({})`	returns the props you should apply to any menu item elements you render. Read more below
`getButtonProps`	`function({})`	returns the props you should apply to any menu toggle button element you render. Read more below
`highlightedIndex`	`number` / `null`	the currently highlighted item
`setHighlightedIndex`	`function(index: number)`	call to set a new highlighted index
`value`	`any` / `Array(any)`	the currently selected item value(s) input
`inputValue`	`string` / `null`	the current value of the `getInputProps` input
`isOpen`	`boolean`	the menu open state
`toggleMenu`	`function(state: boolean)`	toggle the menu open state (if `state` is not provided, then it will be set to the inverse of the current state)
`openMenu`	`function()`	opens the menu
`closeMenu`	`function()`	closes the menu
`clearSelection`	`function()`	clears the selection
`selectItem`	`function(item: any)`	selects the given item
`selectItemAtIndex`	`function(index: number)`	selects the item at the given index
`selectHighlightedItem`	`function()`	selects the item that is currently highlighted

The functions below 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)}}).

`getRootProps`

Most of the time, you can just render a div yourself and Autocompletely 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.

Required 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} />

`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.

`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 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: You can definitely get by without using this (just provide an id to your input and the same htmlFor to your label and you'll be good with accessibility). However, we include this so you don't forget and it makes things a little nicer for you. You're welcome 😀

`getItemProps`

This method should be applied to any menu items you render. You pass it an object and that object must contain index (number) and value (anything) properties.

Required properties:

index: this is how downshift keeps track of your item when updating the highlightedIndex as the user keys around.
value: this is the item data that will be selected when the user selects a particular item.

`getButtonProps`

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. The aria-label prop is in English. You should probably override this yourself so you can provide translations:

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

State Props

You can pass some props which normally the downshift will manage for you. If you pass these props, then they become "controlled" props. In this situation, downshift will no longer update them directly and will instead call your onStateChange handler and expect you to update them. This can be useful if you want to control the component externally (like selecting an item from another part of the UI).

State Props are labeled above with state prop

Examples

Examples exist on codesandbox.io:

If you would like to add an example, follow these steps:

Fork this codesandbox
Update the code for your example (add some form of documentation to explain what it is)
Update the title and description
Add the tag: downshift:example

Inspiration

I was heavily inspired by Ryan Florence and his talk entitled: "Compound Components". 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:

Contributors

Thanks goes to these people (emoji key):

_{Kent C. Dodds} 💻 📖 🚇 ⚠️	_{Ryan Florence} 🤔	_{Jared Forsyth} 🤔 📖	_{Jack Moore} 💡	_{Travis Arnold} 💻 📖	_{Jeremy Gayed} 💡	_{Haroen Viaene} 💡
_monssef 💡	_{Federico Zivolo} 📖	_{Divyendu Singh} 💡	_{Muhammad Salman} 💻	_{João Alberto} 💻	_{Bernard Lin} 💻 📖	_{Geoff Davis} 💡
_Anup 📖	_{Ferdinand Salis} 🐛 💻