Select2 is a jQuery based replacement for select boxes. It supports searching, remote data sets, and infinite scrolling of results.
Select2 can take a regular select box like this:
and turns it into:
with support for quick option filtering via a search box.
<head>
<link href="select2.css" rel="stylesheet"/>
<script src="select2.js"></script>
<script>
$(document).ready(function() { $("#e1").select2(); });
</script>
</head>
<body>
<select id="e1">
<option value="AL">Alabama</option>
...
<option value="WY">Wyoming</option>
</select>
</body>
Select2 also supports multi-value select boxes. The select below is declared with the multiple attribute. Select2 automatically picks up on this:
A placeholder value can be defined and will be displayed until a selection is made:
The placeholder can be declared via a data-placeholder attribute attached to the select, or via the placeholder configuration element as seen in the example code.
When placeholder is used for a non-multi-value select box, it requires that you include an empty <option></option> tag as your first option.
Optionally, a clear button (visible once a selection is made) is available to reset the select box back to the placeholder value.
Select2 supports a minimum input setting which is useful for large remote datasets where short search terms are not very useful:
Various display options of the Select2 component can be changed:
You can set data- attributes to <option> (or <optgroup>) and use them inside templating functions:
<select>
<option value="0" data-foo="bar">option one</option>
...
</select>
function format(state) {
var originalOption = state.element;
return "<img class='flag' src='images/flags/" + state.id.toLowerCase() + ".png' alt='" + $(originalOption).data('foo') + "' />" + state.text;
}
Select2 uses a function to load result data. Here is a trivial example that creates choices that consist of user's input repeated a number of times:
In order to take advantage of custom data loading Select2 should be attached to an input type='hidden' tag, otherwise data is parsed from select's option tags.
Select2 allows the developer to limit the number of items that can be selected in a multi-select control. In the example below only 3 or less items can be selected.
Select2 provides some shortcuts that make it easy to access local data stored in an array instead of having to write a query function mentioned in the example above.
Example below inlines the data by specifying an array in the data element. Items in such an array must have id and text keys.
If your data does not have a text key, an alternative key can be specified as a string:
or as a function:
data can also itself be a function that returns a results object:
Select2 comes with AJAX/JSONP support built in. In this example we will search for repositories using Github's API:
If this example stops working, you have most likely reached the usage limit for the GitHub Search API of 5 requests per minute. Please wait a few minutes and try again.
Select2 uses jQuery's $.ajax function to execute the remote call by default. An alternative transport function can be specified in the ajax settings, or an entirely custom implementation can be built by providing a custom query function instead of using the ajax helper.
Select2 supports lazy-appending of results when the result list is scrolled to the end. In order to enable the remote service must support some sort of a paging mechanism and the query function given to Select2 must take advantage of it. The following example demonstrates how this can be set up. Search for some keyword and then scroll the result list to the end to see more results load:
If this example stops working, you have most likely reached the usage limit for the GitHub Search API of 5 requests per minute. Please wait a few minutes and try again.
Select2 supports methods that allow programmatic control of the component:
change event is triggered on the original element whenever its value is changed by
the user
open event is triggered on the original element whenever the dropdown needs to be opened:
Select2 can be used to quickly set up fields used for tagging.
Note that when tagging is enabled the user can select from pre-existing tags or create a new tag by picking the first choice which is what the user has typed into the search box so far.
Select2 can be set a limit on the number of characters that can be entered per tag.
You would not be able to enter any input of more than 10 characters long.
Select2 supports ability to add choices automatically as the user is typing into the search field. This is especially convenient in the tagging usecase where the user can quickly enter a number of tags by separating them with a comma or a space. Try typing in the search field below and entering a space or a comma.
Note that the separators are defined in the tokenSeparators option.
Note that this example uses the built in tokenizer function, but a custom one can be provided in the options.
Select2 can react to external value changes and keep its selection in-sync. This feature allows Select2 to work seamlessly with front-end frameworks that use data binding between ui components and model values.
This feature is only available when initSelection() function is provided in
the options. This function is needed to map the choice ids set on the element to objects used by
Select2. This function is set by default when Select2 is attached to a select or when
the tags helper function is used.
Select2 supports drag and drop sorting of selected choices. Select2 does not, itself, provide the necessary code to perform dragging and dropping, instead it provides hooks that other libraries can use to provide the behavior. In this example we are using JQuery UI's sortable() plugin.
The sorting is only available when Select2 is attached to a hidden input field.
Unlike other dropdowns on this page, this one matches options only if the term appears in the beginning of the string as opposed to anywhere:
The dropdown below matches on custom attributes of the option tag. For example, the `blue` option can be matched by entering either `blue` or `cyan`:
Unlike other dropdowns on this page, this one filters results by query string normally, but returns the matched results sorted from shortest to longest by string length. Try typing 'e' and seeing how the results are sorted. This function is useful for sorting results by relevance to a user's query.
Select2's width can be set to a percentage of its parent to support responsive design. The two Select2 boxes below are styled to 50% and 75% width respectively.
Select2 will do its best to resolve the percent width specified via a css class, but it is not always possible. The best way to ensure that Select2 is using a percent based width is to inline the style declaration into the tag.
In case that you need to disable certain options so that they can't be selected by the select2 interface, you can now pass in disabled: true with your data. Please note: This also works for incoming values from ajax. When attached to a <select> element, Select2 will respect its <option> elements' disabled property.
In the event that you need to lock certain selections so that they can't be removed by the select2 interface, you can now pass in locked: true with your data. Please note: This also works for incoming values from ajax.
Select2's default matcher will ignore diacritics, making it easier for users to filter results in international selects. Type "aero" into the select below:
| Parameter | Type | Description | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| width | string |
Controls the width style attribute of the Select2 container div. The following values are supported:
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| minimumInputLength | int | Number of characters necessary to start a search. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| maximumInputLength | int | Maximum number of characters that can be entered for an input. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| minimumResultsForSearch | int |
The minimum number of results that must be initially (after opening the dropdown for the first time) populated in order to keep the search field. This is useful for cases where local data is used with just a few results, in which case the search box is not very useful and wastes screen space. The option can be set to a Only applies to single-value select boxes |
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| maximumSelectionSize | int/function |
The maximum number of items that can be selected in a multi-select control. If this number is less than 1 selection is not limited. Once the number of selected items reaches the maximum specified the contents of the dropdown will be populated
by the |
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| placeholder | string |
Initial value that is selected if no other selection is made. The placeholder can also be specified as a Note that because browsers assume the first | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| placeholderOption | function/string |
When attached to a This option is useful when Select2's default of using the first option only if it has no value and no text is not suitable. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| separator | string |
Separator character or string used to delimit ids in | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| allowClear | boolean |
Whether or not a clear button is displayed when the select box has a selection. The button, when clicked, resets the value of the select box back to the placeholder, thus this option is only available when the placeholder is specified. This option only works when the placeholder is specified. When attached to a Also, note that this option only works with non-multi-value based selects because multi-value selects always provide such a button for every selected option. |
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| multiple | boolean |
Whether or not Select2 allows selection of multiple values. When Select2 is attached to a |
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| closeOnSelect | boolean |
If set to false the dropdown is not closed after a selection is made, allowing for rapid selection of multiple items. By default this option is set to Only applies when configured in multi-select mode. |
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| openOnEnter | boolean |
If set to true the dropdown is opened when the user presses the enter key and Select2 is closed. By default this option is enabled. |
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| id | function |
Function used to get the id from the choice object or a string representing the key under which the id is stored.
id(object)
id property that is returned.
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| matcher | function |
Used to determine whether or not the search term matches an option when a built-in query function is used.
The built in query function is used when Select2 is attached to a select, or the local or tags helpers are used.
matcher(term, text, option)
function(term, text) { return text.toUpperCase().indexOf(term.toUpperCase())>=0; }
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| sortResults | function |
Used to sort the results list for searching right before display. Useful for sorting matches by relevance to the user's search term.
sortResults(results, container, query)
function(results, container, query) { return results; }
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| formatSelection | function |
Function used to render the current selection.
formatSelection(object, container)
The default implementation expects the object to have a The implementation may choose to append elements directly to the provided
When attached to a
format(item) {
var originalOption = item.element;
return item.text
}
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| formatResult | function |
Function used to render a result that the user can select.
formatResult(object, container, query)
The default implementation expects the object to have a The implementation may choose to append elements directly to the provided
When attached to a
format(item) {
var originalOption = item.element;
return item.text
}
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| formatResultCssClass | function |
Function used to add css classes to result elements.
formatResultCssClass(object)
By default when attached to a | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| formatNoMatches | string/function |
String containing "No matches" message, or Function used to render the message formatNoMatches(term)
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| formatSearching | string/function |
String containing "Searching..." message, or Function used to render the message that is displayed while search is in progress. formatSearching()
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| formatAjaxError | string/function |
String containing "Loading Failed" message, or Function used to render the message formatAjaxError(jqXHR, textStatus, errorThrown)
For more info on the parameters, refer to the JQuery API Documentation. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| formatInputTooShort | string/function |
String containing "Search input too short" message, or Function used to render the message. formatInputTooShort(term, minLength)
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| formatInputTooLong | string/function |
String containing "Search input too long" message, or Function used to render the message. formatInputTooLong(term, maxLength)
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| formatSelectionTooBig | string/function |
String containing "You cannot select any more choices" message, or Function used to render the message. formatSelectionTooBig(maxSize)
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| formatLoadMore | string/function |
String containing "Loading more results…" message, or Function used to render the message. formatLoadMore(pageNumber)
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| createSearchChoice | function |
Creates a new selectable choice from user's search term. Allows creation of choices not available via the query
function. Useful when the user can create choices on the fly, eg for the 'tagging' usecase.
createSearchChoice(term)
undefined or null no choice will be created. If a new
choice is created it is displayed first in the selection list so that user may select it by simply pressing
enter.
When used in combination with | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| createSearchChoicePosition | string|function |
Define the position where to insert element created by createSearchChoice. The following values are supported:
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| initSelection | function |
Called when Select2 is created to allow the user to initialize the selection based on the value of the
element select2 is attached to.
Essentially this is an initSelection(element, callback)
This function will only be called when there is initial input to be processed. Here is an example implementation used for tags. Tags are the simplest form of data where the id is also the text:
$("#tags").select2({
initSelection : function (element, callback) {
var data = [];
$(element.val().split(",")).each(function () {
data.push({id: this, text: this});
});
callback(data);
}
});
// Or for single select elements:
$("#select").select2({
initSelection : function (element, callback) {
var data = {id: element.val(), text: element.val()};
callback(data);
}
});
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| tokenizer | function |
A tokenizer function can process the input typed into the search field after every keystroke and extract
and select choices. This is useful, for example, in tagging scenarios where the user can create tags quickly
by separating them with a comma or a space instead of pressing enter.
Tokenizer only applies to multi-selects. tokenizer(input, selection, selectCallback, opts)
tokenSeparators and createSearchChoice
options are specified. The default tokenizer will split the string using any separator in tokenSeparators
and will create and select choice objects using createSearchChoice option. It will also
ignore duplicates, silently swallowing those tokens.
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| tokenSeparators | array |
An array of strings that define token separators for the default tokenizer
function. By default, this option is set to an empty array which means tokenization using the default
tokenizer is disabled. Usually it is sensible to set this option to a value similar to [',', ' '].
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| query | function |
Function used to query results for the search term.
query(options)
In order for this function to work Select2 should be attached to a
Example Data
{
more: false,
results: [
{ id: "CA", text: "California" },
{ id: "AL", text: "Alabama" }
]
}
Example Hierarchical Data
{
more: false,
results: [
{ text: "Western", children: [
{ id: "CA", text: "California" },
{ id: "AZ", text: "Arizona" }
] },
{ text: "Eastern", children: [
{ id: "FL", text: "Florida" }
] }
]
}
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| ajax | object |
Options for the built in ajax query function. This object acts as a shortcut for having to manually write a function that performs ajax requests. The built-in function supports more advanced features such as throttling and dropping out-of-order responses.
In order for this function to work Select2 should be attached to a For documentation of the data format see the query function. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| data | array/object |
Options for the built in query function that works with arrays.
If this element contains an array, each element in the array must contain Alternatively, this element can be specified as an object in which | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| tags | array/function |
Puts Select2 into 'tagging'mode where the user can add new choices and pre-existing tags are provided via
this options attribute which is either an array or a function that returns an
array of objects or strings. If strings are used instead of objects
they will be converted into an object that has an id and text attribute equal
to the value of the string.
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| containerCss | function/object | Inline css that will be added to select2's container. Either an object containing css property/value key pairs or a function that returns such an object. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| containerCssClass | function/string | Css class that will be added to select2's container tag. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| dropdownCss | function/object | Inline css that will be added to select2's dropdown container. Either an object containing css property/value key pairs or a function that returns such an object. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| dropdownCssClass | function/string | Css class that will be added to select2's dropdown container. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| dropdownAutoWidth | boolean |
When set to true attempts to automatically size the width of the dropdown based on content inside.
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| adaptContainerCssClass | function |
Function that filters/renames css classes as they are copied from the source tag to the select2 container tag.
adaptContainerCssClass(clazz)
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| adaptDropdownCssClass | function |
Function that filters/renames css classes as they are copied from the source tag to the select2 dropdown tag.
adaptDropdownCssClass(clazz)
null thereby filtering out all classes.
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| escapeMarkup | function |
String escapeMarkup(String markup)
Function used to post-process markup returned from formatter functions. By default this function escapes html entities to prevent javascript injection. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| selectOnBlur | boolean |
Set to | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| loadMorePadding | integer |
Defines how many pixels need to be below the fold before the next page is loaded. The default value is 0 which means the result list needs to be scrolled all the way to the bottom for the next page of results to be loaded. This option can be used to trigger the load sooner, possibly resulting in a smoother user experience.
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| nextSearchTerm | function |
Function used to determine what the next search term should be.
Here is an example implementation used to display the current search term when the dropdown is opened:
function displayCurrentValue(selectedObject, currentSearchTerm) {
return currentSearchTerm;
}
$("#e1").select2({
nextSearchTerm: displayCurrentValue
});
Function can be used when the dropdown is configured in single and multi-select mode. It is triggered after selecting an item. In single mode it is also triggered after initSelection (when provided). |
Gets or sets the selection. If the value parameter is not specified, the id attribute of the currently selected element is returned. If the value parameter is specified it will become the current selection.
| Parameter | Type | Description | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| value (optional) | object |
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| triggerChange (optional) | boolean | Whether or not a change event should be triggered. false by default. |
val method invoked on a single-select with an unset value will return "", while a val method invoked on an empty multi-select will return [].
alert("Selected value is: "+$("#e8").select2("val")); $("#e8").select2("val", "CA");
Notice that in order to use this method you must define the initSelection function in the options so Select2 knows how to transform the id of the object you pass in val() to the full object it needs to render selection. If you are attaching to a select element this function is already provided for you.
Gets or sets the selection. Analogous to val method, but works with objects instead of ids.
data method invoked on a single-select with an unset value will return null, while a data method invoked on an empty multi-select will return [].
Reverts changes to DOM done by Select2. Any selection done via Select2 will be preserved.
Opens the dropdown.
Closes the dropdown.
Enables or disables Select2 and its underlying form component based on the boolean parameter.
Toggles readonly mode on Select2 and its underlying form component based on the boolean parameter.
Retrieves the main container element that wraps all of DOM added by Select2
Example: console.log($("#tags").select2("container"));
Notifies Select2 that a drag and drop sorting operation has started. Select2 will hide all non-selection list items such as the search container, etc.
Example: $("#tags").select2("onSortStart");
Notifies Select2 that a drag and drop sorting operation has finished. Select2 will re-display any elements previously hidden and update the selection of the element it is attached to.
Example: $("#tags").select2("onSortEnd");
Executes a new search using the provided value.
Example: $("#tags").select2("search","California");
Fired when selection is changed.
The event object contains the following custom properties:
Fired before the dropdown is shown.
The event listener can prevent the opening by calling preventDefault() on the supplied event object.
Fired after the dropdown is shown.
Fired after the dropdown is closed.
Fired when a choice is highlighted in the dropdown.
The event object contains the following custom properties:
Fired when a choice is being selected in the dropdown, but before any modification has been made to the selection.
This event is used to allow the user to reject selection by calling event.preventDefault()
The event object contains the following custom properties:
Fired when a choice is being cleared in the dropdown, but before any modification has been made to the selection.
This event is used to allow the user to reject the clear by calling event.preventDefault()
For the clear button to be visible the allowClear option needs to be true.
Fired when a choice is about to be removed in the dropdown/input, but before any removal of the choice has been made.
This event is used to allow the user to reject removal by calling event.preventDefault()
The event object contains the following custom properties:
Fired when a choice is removed or cleared.
The event object contains the following custom properties:
Fired when query function is done loading the data and the results list has been updated
The event object contains the following custom properties:
Fired when the control is focussed.
Fired when the control is blurred.
$.fn.select2.defaults object. Properties changed in this object (same properties configurable through the constructor) will take effect for every instance created after the change.