jQuery.ajaxTransport()
Creates an object that handles the actual transmission of Ajax data.
jQuery.ajaxTransport(dataType, function(optionsPlainObject, originalOptionsPlainObject, jqXHRjqXHR))π‘’ undefined
dataType
String A string identifying the data type to use
function(optionsPlainObject, originalOptionsPlainObject, jqXHRjqXHR)
Function A handler to return the new transport object to use with the data type provided in the first argument.A transport is an object that provides two methods, send and abort, that are used internally by $.ajax() to issue requests. A transport is the most advanced way to enhance $.ajax() and should be used only as a last resort when prefilters and converters are insufficient.
Since each request requires its own transport object instance, transports cannot be registered directly. Therefore, you should provide a function that returns a transport instead.
Transports factories are registered using $.ajaxTransport(). A typical registration looks like this:
$.ajaxTransport( dataType, function( options, originalOptions, jqXHR ) {
if( /* transportCanHandleRequest */ ) {
return {
send: function( headers, completeCallback ) {
// Send code
},
abort: function() {
// Abort code
}
};
}
});where:
optionsare the request optionsoriginalOptionsare the options as provided to the$.ajax()method, unmodified and, thus, without defaults from ajaxSettingsjqXHRis the jqXHR object of the requestheadersis an object of (key-value) request headers that the transport can transmit if it supports itcompleteCallbackis the callback used to notify Ajax of the completion of the request
completeCallback has the following signature:
function( status, statusText, responses, headers ) {
}
where:
statusis the HTTP status code of the response, like 200 for a typical success, or 404 for when the resource is not found.statusTextis the statusText of the response.responses(Optional) is An object containing dataType/value that contains the response in all the formats the transport could provide (for instance, a native XMLHttpRequest object would set responses to{ xml: XMLData, text: textData }for a response that is an XML document)headers(Optional) is a string containing all the response headers if the transport has access to them (akin to whatXMLHttpRequest.getAllResponseHeaders()would provide).
Just like prefilters, a transport's factory function can be attached to a specific dataType:
$.ajaxTransport("script", function (options, originalOptions, jqXHR) {
// Will only be called for script requests
});
The following example shows how a minimal image transport could be implemented:
$.ajaxTransport("image", function (s) {
if (s.type === "GET" && s.async) {
var image;
return {
send: function (_, callback) {
image = new Image();
function done(status) {
if (image) {
var statusText = status === 200 ? "success" : "error",
tmp = image;
image =
image.onreadystatechange =
image.onerror =
image.onload =
null;
callback(status, statusText, { image: tmp });
}
}
image.onreadystatechange = image.onload = function () {
done(200);
};
image.onerror = function () {
done(404);
};
image.src = s.url;
},
abort: function () {
if (image) {
image =
image.onreadystatechange =
image.onerror =
image.onload =
null;
}
},
};
}
});
Handling Custom Data Types
The jQuery Ajax implementation comes with a set of standard dataTypes, such as text, json, xml, and html.
Use the converters option in $.ajaxSetup() to augment or modify the data type conversion strategies used by $.ajax().
The unminified jQuery source itself includes a list of default converters, which effectively illustrates how they can be used:
// List of data converters
// 1) Key format is "source_type destination_type"
// (a single space in-between)
// 2) The catchall symbol "*" can be used for source_type
converters: {
// Convert anything to text
"* text": window.String,
// Text to html (true = no transformation)
"text html": true,
// Evaluate text as a json expression
"text json": jQuery.parseJSON,
// Parse text as xml
"text xml": jQuery.parseXML
}When you specify a converters option globally in $.ajaxSetup() or per call in $.ajax(), the object will map onto the default converters, overwriting those you specify and leaving the others intact.
For example, the jQuery source uses $.ajaxSetup() to add a converter for "text script":
jQuery.ajaxSetup({
accepts: {
script: "text/javascript, application/javascript",
},
contents: {
script: /javascript/,
},
converters: {
"text script": jQuery.globalEval,
},
});