Christopher Baines
Christopher Baines

Living in the UK, I enjoy cats, coding and good company.

cbaines.net/ projects/ osm/ leaflet-soton/ resources/ typeahead.js/ doc/ jquery typeahead

jQuery#typeahead

The UI component of typeahead.js is a available as a jQuery plugin. It's responsible for rendering suggestions and handling DOM interactions.

Table of Contents

Features

  • Displays suggestions to end-users as they type
  • Shows top suggestion as a hint (i.e. background text)
  • Supports custom templates to allow for UI flexibility
  • Works well with RTL languages and input method editors
  • Highlights query matches within the suggestion
  • Triggers custom events

Specification

In an effort to take advantage of the pre-existing knowledge of typeahead.js users, the behavior of the typeahead.js UI is modeled after google.com's search box. Below is pseudocode that details how the UI reacts to pertinent events.

Input Control Gains Focus

activate typeahead

Input Control Loses Focus

deactivate typeahead
close dropdown menu
remove hint
clear suggestions from dropdown menu

Value of the Input Control Changes

IF query satisfies minLength requirement THEN
  request suggestions for new query

  IF suggestions are available THEN
    render suggestions in dropdown menu
    open dropdown menu 
    update hint
  ELSE
    close dropdown menu 
    clear suggestions from dropdown menu
    remove hint
  ENDIF
ELSE
  close dropdown menu 
  clear suggestions from dropdown menu
  remove hint
ENDIF

Up Arrow is Keyed

IF dropdown menu is open THEN
  move dropdown menu cursor up 1 suggestion
ELSE
  request suggestions for current query

  IF suggestions are available THEN
    render suggestions in dropdown menu
    open dropdown menu 
    update hint
  ENDIF
ENDIF

Down Arrow is Keyed

IF dropdown menu is open THEN
  move dropdown menu cursor down 1 suggestion
ELSE
  request suggestions for current query

  IF suggestions are available THEN
    render suggestions in dropdown menu
    open dropdown menu 
    update hint
  ENDIF
ENDIF

Left Arrow is Keyed

IF detected query language direction is right-to-left THEN
  IF hint is being shown THEN
    IF text cursor is at end of query THEN
      autocomplete query to hint
    ENDIF
  ENDIF
ENDIF

Right Arrow is Keyed

IF detected query language direction is left-to-right THEN
  IF hint is being shown THEN
    IF text cursor is at the end of the query THEN
      autocomplete query to hint
    ENDIF
  ENDIF
ENDIF

Tab is Keyed

IF dropdown menu cursor is on suggestion THEN
  close dropdown menu
  update query to display key of suggestion
  remove hint
ELSIF hint is being shown THEN
  autocomplete query to hint
ENDIF

Enter is Keyed

IF dropdown menu cursor is on suggestion THEN
  close dropdown menu
  update query to display key of suggestion
  remove hint
  prevent default browser action e.g. form submit
ENDIF

Esc is Keyed

close dropdown menu
remove hint

Suggestion is Clicked

update query to display key of suggestion
close dropdown menu
remove hint

Usage

API

jQuery#typeahead(options, [*datasets])

Turns any input[type="text"] element into a typeahead. options is an options hash that's used to configure the typeahead to your liking. Refer to Options for more info regarding the available configs. Subsequent arguments (*datasets), are individual option hashes for datasets. For more details regarding datasets, refer to Datasets.

$('.typeahead').typeahead({
  minLength: 3,
  highlight: true,
},
{
  name: 'my-dataset',
  source: mySource
});

jQuery#typeahead('destroy')

Removes typeahead functionality and reverts the input element back to its original state.

$('.typeahead').typeahead('destroy');

jQuery#typeahead('open')

Opens the dropdown menu of typeahead. Note that being open does not mean that the menu is visible. The menu is only visible when it is open and has content.

$('.typeahead').typeahead('open');

jQuery#typeahead('close')

Closes the dropdown menu of typeahead.

$('.typeahead').typeahead('close');

jQuery#typeahead('val')

Returns the current value of the typeahead. The value is the text the user has entered into the input element.

var myVal = $('.typeahead').typeahead('val');

jQuery#typeahead('val', val)

Sets the value of the typeahead. This should be used in place of jQuery#val.

$('.typeahead').typeahead('val', myVal);

jQuery.fn.typeahead.noConflict()

Returns a reference to the typeahead plugin and reverts jQuery.fn.typeahead to its previous value. Can be used to avoid naming collisions.

var typeahead = jQuery.fn.typeahead.noConflict();
jQuery.fn._typeahead = typeahead;

Options

When initializing a typeahead, there are a number of options you can configure.

  • highlight – If true, when suggestions are rendered, pattern matches for the current query in text nodes will be wrapped in a strong element with tt-highlight class. Defaults to false.

  • hint – If false, the typeahead will not show a hint. Defaults to true.

  • minLength – The minimum character length needed before suggestions start getting rendered. Defaults to 1.

Datasets

A typeahead is composed of one or more datasets. When an end-user modifies the value of a typeahead, each dataset will attempt to render suggestions for the new value.

For most use cases, one dataset should suffice. It's only in the scenario where you want rendered suggestions to be grouped in the dropdown menu based on some sort of categorical relationship that you'd need to use multiple datasets. For example, on twitter.com, the search typeahead groups results into recent searches, trends, and accounts – that would be a great use case for using multiple datasets.

Datasets can be configured using the following options.

  • source – The backing data source for suggestions. Expected to be a function with the signature (query, cb). It is expected that the function will compute the suggestion set (i.e. an array of JavaScript objects) for query and then invoke cb with said set. cb can be invoked synchronously or asynchronously. A Bloodhound suggestion engine can be used here, to learn how, see Bloodhound Integration. Required.

  • name – The name of the dataset. This will be appended to tt-dataset- to form the class name of the containing DOM element. Must only consist of underscores, dashes, letters (a-z), and numbers. Defaults to a random number.

  • displayKey – For a given suggestion object, determines the string representation of it. This will be used when setting the value of the input control after a suggestion is selected. Can be either a key string or a function that transforms a suggestion object into a string. Defaults to value.

  • templates – A hash of templates to be used when rendering the dataset. Note a precompiled template is a function that takes a JavaScript object as its first argument and returns a HTML string.

    • empty – Rendered when 0 suggestions are available for the given query. Can be either a HTML string or a precompiled template. If it's a precompiled template, the passed in context will contain query.

    • footer– Rendered at the bottom of the dataset. Can be either a HTML string or a precompiled template. If it's a precompiled template, the passed in context will contain query and isEmpty.

    • header – Rendered at the top of the dataset. Can be either a HTML string or a precompiled template. If it's a precompiled template, the passed in context will contain query and isEmpty.

    • suggestion – Used to render a single suggestion. If set, this has to be a precompiled template. The associated suggestion object will serve as the context. Defaults to the value of displayKey wrapped in a p tag i.e. <p>{{value}}</p>.

Custom Events

The typeahead component triggers the following custom events.

  • typeahead:opened – Triggered when the dropdown menu of a typeahead is opened.

  • typeahead:closed – Triggered when the dropdown menu of a typeahead is closed.

  • typeahead:cursorchanged – Triggered when the dropdown menu cursor is moved to a different suggestion. The event handler will be invoked with 3 arguments: the jQuery event object, the suggestion object, and the name of the dataset the suggestion belongs to.

  • typeahead:selected – Triggered when a suggestion from the dropdown menu is selected. The event handler will be invoked with 3 arguments: the jQuery event object, the suggestion object, and the name of the dataset the suggestion belongs to.

  • typeahead:autocompleted – Triggered when the query is autocompleted. Autocompleted means the query was changed to the hint. The event handler will be invoked with 3 arguments: the jQuery event object, the suggestion object, and the name of the dataset the suggestion belongs to.

All custom events are triggered on the element initialized as a typeahead.

Look and Feel

Below is a faux mustache template describing the DOM structure of a typeahead dropdown menu. Keep in mind that header, footer, suggestion, and empty come from the provided templates detailed here.

<span class="tt-dropdown-menu">
  {{#datasets}}
    <div class="tt-dataset-{{name}}">
      {{{header}}}
      <span class="tt-suggestions">
        {{#suggestions}}
          <div class="tt-suggestion">{{{suggestion}}}</div>
        {{/suggestions}}
        {{^suggestions}}
          {{{empty}}}
        {{/suggestions}}
      </span>
      {{{footer}}}
    </div>
  {{/datasets}}
</span>

When an end-user mouses or keys over a .tt-suggestion, the class tt-cursor will be added to it. You can use this class as a hook for styling the "under cursor" state of suggestions.

Bloodhound Integration

Because datasets expect their source to be a function, you cannot directly pass a Bloodhound suggestion engine in as source. Rather, you'll need to pass the suggestion engine's typeahead adapter:

var engine = new Bloodhound({ /* options */ });

engine.initialize();

$('.typeahead').typeahead(null, {
  source: engine.ttAdapter()
});