accessible-autocomplete

Accessible autocomplete

accessible-autocomplete is a JavaScript autocomplete built from the ground up to be accessible. The design goals are:

• Accessibility: Following WAI-ARIA best practices and testing with assistive technologies.
• User experience: Supporting a wide variety of user needs.
• Compatibility: Working with as many browsers, devices, and assistive technologies as possible.

Try out the examples!

Installation / usage

Using npm

Install it by running:

npm install --save accessible-autocomplete

Import it using a module system like Webpack:

import accessibleAutocomplete from 'accessible-autocomplete'

Or using a script tag:

<script type="text/javascript" src="node_modules/accessible-autocomplete/dist/accessible-autocomplete.min.js"></script>

And then call the accessibleAutocomplete function, providing a suggestion engine:

function suggest (query, populateResults) {
  const results = [
    'France',
    'Germany',
    'United Kingdom'
  ]
  const filteredResults = results.filter(result => result.indexOf(query) !== -1)
  populateResults(filteredResults)
}

accessibleAutocomplete({
  element: document.querySelector('#my-autocomplete-container'),
  id: 'my-autocomplete',
  source: suggest
})

Don't forget to include the stylesheet:

<link rel="stylesheet" href="node_modules/accessible-autocomplete/dist/accessible-autocomplete.min.css" />

API documentation

Required options

element

Type: HTMLElement

The container element in which the autocomplete will be rendered in.

id (default: 'autocomplete')

Type: string

The id to assign to the autocomplete input field, to use with a <label for=id>. Not required if using enhanceSelectElement.

source

Type: Function

Arguments: query: string, populateResults: Function

Similar to the source argument for typeahead.js, a backing data source for suggestions. query is what gets typed into the input field, which will callback to populateResults synchronously with the array of string results to display in the menu.

An example of a simple suggestion engine:

function suggest (query, populateResults) {
  const results = [
    'France',
    'Germany',
    'United Kingdom'
  ]
  const filteredResults = results.filter(result => result.indexOf(query) !== -1)
  populateResults(filteredResults)
}

Other options

autoselect (default: false)

Type: Boolean

Set to true to highlight the first option when the user types in something and receives results. Pressing enter will select it.

confirmOnBlur (default: true)

Type: Boolean

The autocomplete will confirm the currently selected option when the user clicks outside of the component. Set to false to disable.

cssNamespace (default: 'autocomplete')

Type: string

Use this property to override the BEM block name that the JavaScript component will use. You will need to rewrite the CSS class names to use your specified block name.

defaultValue (default: '')

Type: string

Specify a string to prefill the autocomplete with.

displayMenu (default: 'inline')

Type: 'inline' | 'overlay'

You can set this property to specify the way the menu should appear, whether inline or as an overlay.

minLength (default: 0)

Type: number

The minimum number of characters that should be entered before the autocomplete will attempt to suggest options. When the query length is under this, the aria status region will also provide helpful text to the user informing them they should type in more.

name (default: 'input-autocomplete')

Type: string

The name for the autocomplete input field, to use with a parent <form>.

onConfirm (default: () => {})

Type: Function

Arguments: confirmed: Object

This function will be called when the user confirms an option, with the option they've confirmed.

placeholder (default: '') :warning: not recommended :warning:

Type: string

This option will populate the placeholder attribute on the input element.

We think placeholders have usability issues and that there are better alternatives to input placeholder text, so we do not recommend using this option.

showNoResultsFound (default: true)

Type: Boolean

The autocomplete will display a "No results found" template when there are no results. Set to false to disable.

templates (default: undefined)

Type:

{
  inputValue: Function,
  suggestion: Function
}

This object defines templates (functions) that are used for displaying parts of the autocomplete.

inputValue is a function that receives one argument, the currently selected suggestion. It returns the string value to be inserted into the input.

suggestion is a function that receives one argument, a suggestion to be displayed. It is used when rendering suggestions, and should return a string, which can contain HTML. :warning: Caution: because this function allows you to output arbitrary HTML, you should make sure it's trusted, and accessible.

Progressive enhancement

If your autocomplete is meant to select from a small list of options (a few hundred), we strongly suggest that you render a <select> menu on the server, and use progressive enhancement.

If you have the following HTML:

<select id="location-picker">
  <option value="fr">France</option>
  <option value="de">Germany</option>
  <option value="gb">United Kingdom</option>
</select>

You can use the accessibleAutocomplete.enhanceSelectElement function to enhance it into an autocomplete:

accessibleAutocomplete.enhanceSelectElement({
  selectElement: document.querySelector('#location-picker')
})

This will:

• Place an autocomplete input field after the specified <select>
• Default the autocomplete autoselect to true
• Default the autocomplete defaultValue to the select's option[selected]
• Default the autocomplete id to the <select>'s id
• Default the autocomplete name attribute to '' to prevent it being included in form submissions
• Default the autocomplete source to use existing <option>s from the <select>
• Hide the <select> using inline display: none
• Set the <select>'s id to ${id}-select to decouple from any <label>
• Upon confirming a value in the autocomplete, update the original <select>

This function takes the same options as accessibleAutocomplete, with the only difference being that it uses selectElement instead of element, which needs to be an instance of HTMLSelectElement.

Note: The accessibleAutocomplete.enhanceSelectElement function is fairly light and wraps the public API for accessibleAutocomplete. If your use case doesn't fit the above defaults, try reading the source and seeing if you can write your own.

Analytics and tracking

The following events get triggered on the input element during the life cycle of the autocomplete:

• onConfirm - This function will be called when the user confirms an option, with the option they've chosen.

Example usage:

accessibleAutocomplete({
  // additional options
  onConfirm: (val) => {
    track(val)
  }
})

Why another autocomplete?

accessible-autocomplete was built after studying many existing solutions and prototyping patches to fix user experience or accessibility issues. It draws heavy inspiration from the following (and a lot of others):

• ljwatson/design-patterns: great accessible experience
• corejavascript/corejs-typeahead: flexible autocomplete/suggestion engine architecture
• JamieAppleseed/selectToAutocomplete: ease of use

Developing locally

Check out the CONTRIBUTING guide for instructions.

If you want to help and want to get more familiar with the codebase, try starting with the "good for beginners" issues.

License

MIT.

Changelog

1.0.2 - 2017-05-12

• Add support for an empty defaultValue when enhancing a select element. By @lennym.