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Ajax Requests - JavaScript API#

Ajax inside Modules#

The Ajax component was designed to be used from inside modules where an object reference is used to delegate request callbacks. This is acomplished through a set of magic methods that are automatically called when the request is created or its state has changed.


The lazy initialization is performed upon the first invocation from the callee, using the magic _ajaxSetup() method to retrieve the basic configuration for this and any future requests.

The data returned by _ajaxSetup() is cached and the data will be used to pre-populate the request data before sending it. The callee can overwrite any of these properties. It is intended to reduce the overhead when issuing request when these requests share the same properties, such as accessing the same endpoint.

// App/Foo.js
define(["Ajax"], function(Ajax) {
  "use strict";

  function Foo() {};
  Foo.prototype = {
    one: function() {
      // this will issue an ajax request with the parameter `value` set to `1`

    two: function() {
      // this request is almost identical to the one issued with `.one()`, but
      // the value is now set to `2` for this invocation only.
      Ajax.api(this, {
        parameters: {
          value: 2

    _ajaxSetup: function() {
      return {
        data: {
          actionName: "makeSnafucated",
          className: "app\\data\\foo\\FooAction",
          parameters: {
            value: 1

  return Foo;

Request Settings#

The object returned by the aforementioned _ajaxSetup() callback can contain these values:


Defaults to {}.

A plain JavaScript object that contains the request data that represents the form data of the request. The parameters key is recognized by the PHP Ajax API and becomes accessible through $this->parameters.


Defaults to application/x-www-form-urlencoded; charset=UTF-8.

The request content type, sets the Content-Type HTTP header if it is not empty.


Defaults to application/json.

The server must respond with the Content-Type HTTP header set to this value, otherwise the request will be treated as failed. Requests for application/json will have the return body attempted to be evaluated as JSON.

Other content types will only be validated based on the HTTP header, but no additional transformation is performed. For example, setting the responseType to application/xml will check the HTTP header, but will not transform the data parameter, you'll still receive a string in _ajaxSuccess!


Defaults to POST.

The HTTP Verb used for this request.


Defaults to an empty string.

Manual override for the request endpoint, it will be automatically set to the Core API endpoint if left empty. If the Core API endpoint is used, the options includeRequestedWith and withCredentials will be force-set to true.


Enabling this parameter for any domain other than the current will trigger a CORS preflight request.

Defaults to false.

Include cookies with this requested, is always true when url is (implicitly) set to the Core API endpoint.


Defaults to false.

When set to true, any pending responses to earlier requests will be silently discarded when issuing a new request. This only makes sense if the new request is meant to completely replace the result of the previous one, regardless of its reponse body.

Typical use-cases include input field with suggestions, where possible values are requested from the server, but the input changed faster than the server was able to reply. In this particular case the client is not interested in the result for an earlier value, auto-aborting these requests avoids implementing this logic in the requesting code.


Defaults to false.

Any failing request will invoke the failure-callback to check if an error message should be displayed. Enabling this option will suppress the general error overlay that reports a failed request.

You can achieve the same result by returning false in the failure-callback.


Defaults to false.

Enabling this option will suppress the loading indicator overlay for this request, other non-"silent" requests will still trigger the loading indicator.


Enabling this parameter for any domain other than the current will trigger a CORS preflight request.

Defaults to true.

Sets the custom HTTP header X-Requested-With: XMLHttpRequest for the request, it is automatically set to true when url is pointing at the WSC API endpoint.


Defaults to null.

Optional callback function that will be invoked for requests that have failed for one of these reasons: 1. The request timed out. 2. The HTTP status is not 2xx or 304. 3. A responseType was set, but the response HTTP header Content-Type did not match the expected value. 4. The responseType was set to application/json, but the response body was not valid JSON.

The callback function receives the parameter xhr (the XMLHttpRequest object) and options (deep clone of the request parameters). If the callback returns false, the general error overlay for failed requests will be suppressed.

There will be no error overlay if ignoreError is set to true or if the request failed while attempting to evaluate the response body as JSON.


Defaults to null.

Optional callback function that will be invoked once the request has completed, regardless if it succeeded or failed. The only parameter it receives is options (the request parameters object), but it does not receive the request's XMLHttpRequest.


Defaults to null.

This semi-optional callback function will always be set to _ajaxSuccess() when invoking Ajax.api(). It receives four parameters: 1. data - The request's response body as a string, or a JavaScript object if contentType was set to application/json. 2. responseText - The unmodified response body, it equals the value for data for non-JSON requests. 3. xhr - The underlying XMLHttpRequest object. 4. requestData - The request parameters that were supplied when the request was issued.


This callback method is automatically called for successful AJAX requests, it receives four parameters, with the first one containing either the response body as a string, or a JavaScript object for JSON requests.


Optional callback function that is invoked for failed requests, it will be automatically called if the callee implements it, otherwise the global error handler will be executed.

Single Requests Without a Module#

The Ajax.api() method expects an object that is used to extract the request configuration as well as providing the callback functions when the request state changes.

You can issue a simple Ajax request without object binding through Ajax.apiOnce() that will destroy the instance after the request was finalized. This method is significantly more expensive for repeated requests and does not offer deriving modules from altering the behavior. It is strongly recommended to always use Ajax.api() for requests to the WSC API endpoint.

<script data-relocate="true">
  require(["Ajax"], function(Ajax) {
      data: {
        actionName: "makeSnafucated",
        className: "app\\data\\foo\\FooAction",
        parameters: {
          value: 3
      success: function(data) {
        elBySel(".some-element").textContent =;

Last update: 2021-01-08