API allows elements to trigger actions on a server

Integrates Seamlessly with UI

API is designed to make the process of integrating data sources to UI components seamless, tying API request state to UI states automatically.

For example adding an API behavior to an input will occur oninput, while a button, will query the server onclick.

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Preserve Templated URLs

API helps you decouple URLs from your code. Use named API actions like get followers instead of URLs like in your code.

$('.button') .api({ action: 'get followers' }) ;

Centrally manage your entire API making sure you aren't caught modifying urls across your codebase. Define your endpoints using an intuitive templating system that automatically passes data found in your UI.

$.fn.api.settings.api = { 'get followers' : '/followers/{id}?results={count}', 'create user' : '/create', 'add user' : '/add/{id}', 'search' : '/query/{query}/{/sort}' };

HTTP 200 is Not Success

Parse your JSON for success conditions before callbacks fire, making sure server errors caught correctly, still trigger error conditions in your front end code.

// Responses without this status will trigger error conditions $.fn.api.settings.successTest = function(response) { return response.status == 'OK'; }

Translate APIs on the Fly

Using a third party API that uses some unruly code? Not a problem! API lets you modify an APIs raw JSON response before it is consumed by your code.

Tools for Third-Party Integrations & Mocking

New powerful callbacks like response and responseAsync let you asynchronously mock responses and trigger the same callbacks as your API.

API Example

Patrick Russel
Patrick lives in San Francisco, and studies french literature.

Creating an API

API Actions

API works by defining a set of server actions which interface elements can query. Actions are usually represented by short phrases, things like save profile, or get followers which correspond to a templated URL resource on the server.

URL variables specified in actions are substituted at run-time allowing individual components to query different URLs.

URLs listed in your API can include required parameters and optional parameters which may be adjusted for each call.

Required Parameters

Uses format {variable}
Will abort the request if they cannot be found.
/* Two required variables */ $.fn.api.settings.api = { 'get followers' : '/followers/{id}?results={count}' };

Optional Parameters

Uses format {/variable}
Will not abort the request if they cannot be found.
Will be removed from the URL automatically if not available.
Any preceding slash before an optional parameter will be removed from the URL, allowing you to include them in resource paths.
/* One required, one optional variable */ $.fn.api.settings.api = { 'get followers' : '/followers/{id}/{/sort}' };

Creating your API

You should define your endpoints once in your application. Usually this is done in a central configuration file included on each page.

These named API endpoints are stored globally in $.fn.api.settings.api.

Keeping your endpoints defined in one place makes sure when you update your application you will only need to update a single location with new URLs.

/* Define API endpoints once globally */ $.fn.api.settings.api = { 'get followers' : '/followers/{id}?results={count}', 'create user' : '/create', 'add user' : '/add/{id}', 'follow user' : '/follow/{id}', 'search' : '/search/?query={value}' };

Using URLs

Named API actions are not required to use API, you can also manually specify the URL for a request and use the same templating:

$('.search.button') .api({ url: '{value}' }) ;

Querying API Actions

The following examples work best while viewing console logs in your web console.

Attaching API Events

API events are triggered by attaching named actions to elements on your page. These actions look up named endpoints in your API translating templated values from your element for each call.

Any element can have an API action attached directly to it. By default the action will occur on the most appropriate event for the type of element. For example a button will call your server onclick, an input oninput, or a form onsubmit.

API actions and data can be specified in Javascript on initialization:

// translates '/follow/{id}' to 'follow/22' $('.follow.button') .api({ action: 'follow user', urlData: { id: 22 } }) ;

API actions and data can also be specified in metadata:

// also calls '/follow/22' $('.follow.button') .api() ;

Specifying DOM Events

If you need to override what action an API event occurs on you can use the on parameter.

API requests for the following demos have been faked using API's response setting to avoid rate throttling from public APIs. No actual data is returned.
$('.follow.button') .api({ action: 'follow user', on: 'mouseenter' }) ;

Calling Immediately

If you require API action to occur immediately use on: 'now'. This will still trigger the same state updates to the invoked element, but will occur immediately.

$('.follow.button') .api({ action: 'follow user', on: 'now' }) ;

Keep in mind passing a new settings object will destroy the previous instance, and all its settings and events. If you want to preserve the previous instance, you can trigger a new request with the query behavior.

// set-up API button with events $('.follow.button') .api({ action: 'follow user' }) ; // do an immediate query $('.follow.button') .api('query') ;

Setting-up Requests

Routing Data to URLs

If your API URLs include templated variables they will be replaced during your request by one of four possible ways, listed in of inheritance.

All parameters used in a URL are encoded using encodeURIComponent by default, to prevent from malicious strings from affecting your query. To disable this feature you can set encodeParameters: false.

1. Automatically Routed URL Variables

Some special values will be automatically replaced if specified in URL actions.

Variable Description Available for
text current text value of element All elements
value current input value of element Input elements
$ = '/search/?query={value}'; $('.routed.example .search input') .api({ action : 'search', stateContext : '.ui.input' }) ;

2. URL Variables Specified in Data Attributes

You can include URL values as HTML5 metadata attributes.

This is often the easiest way to include unique URL data for each triggering element. For example, many follow buttons will trigger the same endpoint, but each will have its own user id.

Only variables specified in your API's URL will be searched for in metadata.
Follow Sally
Follow Jenny
// requests different URLs for each button $('.follow.button') .api({ action: 'follow user' }) ;

3. Settings Specified in Javascript

URL variables and GET/POST data can be specified at run-time in the Javascript object.

$('.follow.button') .api({ action : 'follow user', method : 'POST', // Substituted into URL urlData: { id: 22 }, // passed via POST data: { name: 'Joe Henderson' } }) ;

4. Settings Returned from beforeSend

All run settings, not just URL data, can be adjusted in a special callback beforeSend which occurs before the API request is sent.

An additional callback beforeXHR lets you modify the XHR object before sending. This is different than beforeSend which is used to modify settings before send.
$('.follow.button') .api({ action: 'follow user', beforeSend: function(settings) { settings.urlData = { id: 22 }; return settings; } beforeXHR: function(xhr) { // adjust XHR with additional headers xhr.setRequestHeader ('Authorization', 'Basic XXXXXX'); return xhr; } }) ;

Adjusting Requests

Modifying XHR

An additional callback beforeXHR lets you modify the XHR object before sending. This is useful for adjusting properties of the XHR request like modifying headers, before sending a request.

$('.follow.button') .api({ action: 'follow user', beforeXHR: function(xhr) { // adjust XHR with additional headers xhr.setRequestHeader ('Authorization', 'Basic XXXXXX'); return xhr; } }) ;

Disabling Requests

As a convenience, API will automatically prevent requests from occurring on elements that are currently disabled.

// this will never occur $('.disabled.button') .api({ action: 'follow user' }) ;

Cancelling Requests

BeforeSend can also be used to check for special conditions for a request to be made. If the beforeSend callback returns false, the request will be cancelled.

// set somewhere in your code window.isLoggedIn = false; $('.follow.button') .api({ action: 'follow user', beforeSend: function(settings) { // cancel request if(!isLoggedIn) { $(this).state('flash text', 'Requires Login!'); return false; } } }) ;

Passing Data

1. Routed Form Data

When you use the serializeForm setting or attach API events on a form, API will automatically include the closest form in data sent to the server.

Structured form data is beneficial over jQuery's serialize for several reasons:

  • Serialize Object correctly converts structured form names like name="name[first]" into nested object literals.
  • Structured form data can be modified in Javascript in beforeSend.
  • Form data will automatically be converted to their Javascript equivalents, for instance, checkboxes will be converted to boolean values.
Structured form data requires including macek's serialize object.

Structured Data Example

The following form shows some of the advantages of structured form data mentioned above.

$('form .submit.button') .api({ action: 'create user', serializeForm: true, data: { foo: 'baz' }, beforeSend: function(settings) { // form data is editable in before send if( == '') { = 'New User'; } // open console to inspect object console.log(; return settings; } }) ;

2. Data Routed in Javascript

Server data can be specified directly when initializing an API requests.

$('.form .submit') .api({ data: { session: 22, name: 'Baz' } }) ;

3. Data Added in beforeSend

POST or GET data can be specified using a special callback beforeSend, which can be used to retrieve data before sending a request.

$('.form .submit') .api({ action: 'create user', serializeForm: true, // arbitrary POST/GET same across all requests data: { session: 22 }, // modify data PER element in callback beforeSend: function(settings) { // cancel request if no id if(!$(this).data('id')) { return false; } = $(this).data('id'); return settings; } }) ;

Server Responses

Response Callbacks

Successful responses from the server will trigger onSuccess, invalid results onFailure.

onError will only trigger on XHR errors, but not on invalid JSON responses.

You can use the onResponse callback to adjust the JSON response before being parsed against a success test.

$('.follow.button') .api({ onResponse: function(response) { // make some adjustments to response return response; }, successTest: function(response) { // test whether a JSON response is valid return response.success || false; }, onComplete: function(response) { // always called after XHR complete }, onSuccess: function(response) { // valid response and response.success = true }, onFailure: function(response) { // request failed, or valid response but response.success = false }, onError: function(errorMessage) { // invalid response }, onAbort: function(errorMessage) { // navigated to a new page, CORS issue, or user canceled request } }) ;

Determining JSON Success

API has special success conditions for JSON responses. Instead of providing success and failure callbacks based on the HTTP response of the request, a request is considered successful only if the server's response tells you the action was successful. The response is passed to a validation test successTest which can be used to check the JSON for a valid response.

For example, you might expect all successful JSON responses to return a top level property signifying the success of the response:

You can use the onResponse callback to modify a server's response by returning a new translated response value before it is parsed by a success test.
{ "success": true, "message": "We've retrieved your data from the server" "data": { // payload here } }

You can specify a success test to check for this success value. This most likely will be set globally for all API requests.

$.fn.api.settings.successTest = function(response) { if(response && response.success) { return response.success; } return false; };

Modifying Response JSON

Since version 2.0, API includes an onResponse callback which lets you adjust a server's response before a response is validated, allowing you to transform your response before other callbacks fire. This is useful for situations where an API response cannot be modified, but you need the response to conform with a required JSON structure.

$('') .search({ type : 'category', minCharacters : 3, apiSettings : { url : '//{query}', onResponse : function(githubResponse) { var response = { results : {} } ; if(!githubResponse || !githubResponse.items) { return; } // translate GitHub API response to work with search $.each(githubResponse.items, function(index, item) { var language = item.language || 'Unknown', maxResults = 8 ; if(index >= maxResults) { return false; } // create new language category if(response.results[language] === undefined) { response.results[language] = { name : language, results : [] }; } // add result to category response.results[language].results.push({ title :, description : item.description, url : item.html_url }); }); return response; } } }) ;

Controlling State

UI State

API will automatically add class names for loading and error. This will let you trigger different UI states automatically as an API call progresses.

If you need a different element than the triggering API element to receive state class names, you can specify a different selector using settings.stateContext.

Using stateContext allows you to easily do things like trigger a loading state on a form when a submit button is pressed.

States Included in API Module
State Description API event
loading Indicates a user needs to wait XHR has initialized
error Indicates an error has occurred XHR Request returns error (does not trigger onAbort caused by page change, or if successTest fails). Stays visible for settings.errorDuration
disabled prevents API action none

Text State

Initializing an API action with the state module gives you more granular control over UI states, like setting an activated or de-activated state and the ability to adjust text values for each state:

$('.follow.button') .api({ action: 'follow user' }) .state({ onActivate: function() { $(this).state('flash text'); }, text: { inactive : 'Follow', active : 'Followed', deactivate : 'Unfollow', flash : 'Added follower!' } }) ;
States Included in State Module
State Description Occurs on
inactive Default state
active Selected state Toggled on succesful API request
activate Explains activating action On hover if inactive
deactivate Explains deactivating action On hover if active
hover Explains interaction On hover in all states, overrides activate/deactivate
disabled Indicates element cannot be interacted Triggered programatically. Blocks API requests.
flash Text-only state used to display a temporary message Triggered programatically
success Indicates user action was a success Triggered programatically
warning Indicates there was an issue with a user action Triggered programatically

Advanced Use

Fulfilling Responses

Since version 2.0, API includes two new parameter response and responseAsync which allows you to specify a Javascript object or a function for returning an API response. (These were previously mockResponse and mockResponseAsync.)

$('.sync.mocked .button') .api({ response: { success: true } }) .state({ text: { inactive : 'Off', active : 'On' } }) ;

Using Custom Backends

Using responseAsync you can specify a function which can execute your API request. This allows for you to use custom backends or wrappers outside of $.ajax for integrating API requests.

$('.async.mocked .button') .api({ responseAsync: function(settings, callback) { var response = { success: true }; // do any asynchronous task here setTimeout(function() { callback(response); }, 500); } }) .state({ text: { inactive : 'Off', active : 'On' } }) ;


All the following behaviors can be called using the syntax:

$('.your.element') .api('behavior name', argumentOne, argumentTwo) ;
Behavior Description
query Execute query using existing API settings
add url data(url, data) Adds data to existing templated url and returns full url string
get request Gets promise for current API request
abort Aborts current API request
reset Removes loading and error state from element
was cancelled Returns whether last request was cancelled
was failure Returns whether last request was failure
was successful Returns whether last request was successful
was complete Returns whether last request was completed
is disabled Returns whether element is disabled
is mocked Returns whether element response is mocked
is loading Returns whether element is loading
set loading Sets loading state to element
set error Sets error state to element
remove loading Removes loading state to element
remove error Removes error state to element
get event Gets event that API request will occur on
get url encoded value(value) Returns encodeURIComponent value only if value passsed is not already encoded
read cached response(url) Reads a locally cached response for a URL
write cached response(url, response) Writes a cached response for a URL
create cache Creates new cache, removing all locally cached URLs
destroy Removes API settings from the page and all events



You can pass in any standard jQuery AJAX setting like timeout or contentType to API's settings and it will be automatically passed to the request's AJAX call.


Default Description
on auto When API event should occur
cache true Can be set to 'local' to cache successful returned AJAX responses when using a JSON API. This helps avoid server roundtrips when API endpoints will return the same results when accessed repeatedly. Setting to false, will add cache busting parameters to the URL.
stateContext this UI state will be applied to this element, defaults to triggering element.
encodeParameters true Whether to encode parameters with encodeURIComponent before adding into url string
defaultData true Whether to automatically include default data like {value} and {text}
serializeForm false Whether to serialize closest form and include in request
throttle 0 How long to wait when a request is made before triggering request, useful for rate limiting oninput
throttleFirstRequest true When set to false will not delay the first request made, when no others are queued
interruptRequests false Whether an API request can occur while another request is still pending
loadingDuration 0 Minimum duration to show loading indication
hideError auto The default auto will automatically remove error state after error duration, unless the element is a form
errorDuration 2000 Setting to true, will not remove error. Setting to a duration in milliseconds to show error state after request error.

Request Settings

Default Description Possible Values
action false Named API action for query, originally specified in $.fn.settings.api String or false
url false Templated URL for query, will override specified action String or false
urlData false Variables to use for replacement
response false Can be set to a Javascript object which will be returned automatically instead of requesting JSON from server {} or false
responseAsync(settings, callback) false When specified, this function can be used to retrieve content from a server and return it asynchronously instead of a standard AJAX call. The callback function should return the server response. function or false
mockResponse false Alias of response
mockResponseAsync false Alias of responseAsync
method get Method for transmitting request to server Any valid http method
dataType JSON Expected data type of response xml, json, jsonp, script, html, text
data {} POST/GET Data to Send with Request


Context Description
beforeSend(settings) initialized element Allows modifying settings before request, or cancelling request
beforeXHR(xhrObject) Allows modifying XHR object for request
onRequest(promise, xhr) state context Callback that occurs when request is made. Receives both the API success promise and the XHR request promise.
onResponse(response) state context Allows modifying the server's response before parsed by other callbacks to determine API event success
successTest(response) Determines whether completed JSON response should be treated as successful
onSuccess(response, element, xhr) state context Callback after successful response, JSON response must pass successTest
onComplete(response, element, xhr) state context Callback on request complete regardless of conditions
onFailure(response, element) state context Callback on failed response, or JSON response that fails successTest
onError(errorMessage, element, xhr) state context Callback on server error from returned status code, or XHR failure.
onAbort(errorMessage, element, xhr) state context Callback on abort caused by user clicking a link or manually cancelling request.


These settings are native to all modules, and define how the component ties content to DOM attributes, and debugging settings for the module.

Default Description
name API Name used in log statements
namespace api Event namespace. Makes sure module teardown does not effect other events attached to an element.
regExp : { required: /\{\$*[A-z0-9]+\}/g, optional: /\{\/\$*[A-z0-9]+\}/g, }
Regular expressions used for template matching
selector: { disabled : '.disabled', form : 'form' }
Selectors used to find parts of a module
className: { loading : 'loading', error : 'error' }
Class names used to determine element state
metadata: { action : 'action', url : 'url' }
Metadata used to store XHR and response promise
silent False Silences all console output including error messages, regardless of other debug settings.
debug false Debug output to console
performance true Show console.table output with performance metrics
verbose false Debug output includes all internal behaviors
// errors error : { beforeSend : 'The before send function has aborted the request', error : 'There was an error with your request', exitConditions : 'API Request Aborted. Exit conditions met', JSONParse : 'JSON could not be parsed during error handling', legacyParameters : 'You are using legacy API success callback names', missingAction : 'API action used but no url was defined', missingSerialize : 'Required dependency jquery-serialize-object missing, using basic serialize', missingURL : 'No URL specified for API event', noReturnedValue : 'The beforeSend callback must return a settings object, beforeSend ignored.', parseError : 'There was an error parsing your request', requiredParameter : 'Missing a required URL parameter: ', statusMessage : 'Server gave an error: ', timeout : 'Your request timed out' }

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