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request.js
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request.js
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/** section: Ajax
* class Ajax.Request
*
* Initiates and processes an Ajax request.
*
* [[Ajax.Request]] is a general-purpose class for making HTTP requests which
* handles the life-cycle of the request, handles the boilerplate, and lets
* you plug in callback functions for your custom needs.
*
* In the optional `options` hash, you usually provide an `onComplete` and/or
* `onSuccess` callback, unless you're in the edge case where you're getting a
* JavaScript-typed response, that will automatically be `eval`'d.
*
* For a full list of common options and callbacks, see "Ajax options" heading
* of the [[Ajax section]].
*
* ##### A basic example
*
* new Ajax.Request('/your/url', {
* onSuccess: function(response) {
* // Handle the response content...
* }
* });
*
* ##### Request life-cycle
*
* Underneath our nice requester objects lies, of course, `XMLHttpRequest`. The
* defined life-cycle is as follows:
*
* 1. Created
* 2. Initialized
* 3. Request sent
* 4. Response being received (can occur many times, as packets come in)
* 5. Response received, request complete
*
* As you can see under the "Ajax options" heading of the [[Ajax section]],
* Prototype's AJAX objects define a whole slew of callbacks, which are
* triggered in the following order:
*
* 1. `onCreate` (this is actually a callback reserved to [[Ajax.Responders]])
* 2. `onUninitialized` (maps on Created)
* 3. `onLoading` (maps on Initialized)
* 4. `onLoaded` (maps on Request sent)
* 5. `onInteractive` (maps on Response being received)
* 6. `on`*XYZ* (numerical response status code), onSuccess or onFailure (see below)
* 7. `onComplete`
*
* The two last steps both map on *Response received*, in that order. If a
* status-specific callback is defined, it gets invoked. Otherwise, if
* `onSuccess` is defined and the response is deemed a success (see below), it
* is invoked. Otherwise, if `onFailure` is defined and the response is *not*
* deemed a sucess, it is invoked. Only after that potential first callback is
* `onComplete` called.
*
* ##### A note on portability
*
* Depending on how your browser implements `XMLHttpRequest`, one or more
* callbacks may never be invoked. In particular, `onLoaded` and
* `onInteractive` are not a 100% safe bet so far. However, the global
* `onCreate`, `onUninitialized` and the two final steps are very much
* guaranteed.
*
* ##### `onSuccess` and `onFailure`, the under-used callbacks
*
* Way too many people use [[Ajax.Request]] in a similar manner to raw XHR,
* defining only an `onComplete` callback even when they're only interested in
* "successful" responses, thereby testing it by hand:
*
* // This is too bad, there's better!
* new Ajax.Request('/your/url', {
* onComplete: function(response) {
* if (200 == response.status)
* // yada yada yada
* }
* });
*
* First, as described below, you could use better "success" detection: success
* is generally defined, HTTP-wise, as either no response status or a "2xy"
* response status (e.g., 201 is a success, too). See the example below.
*
* Second, you could dispense with status testing altogether! Prototype adds
* callbacks specific to success and failure, which we listed above. Here's
* what you could do if you're only interested in success, for instance:
*
* new Ajax.Request('/your/url', {
* onSuccess: function(response) {
* // yada yada yada
* }
* });
*
* ##### Automatic JavaScript response evaluation
*
* If an Ajax request follows the _same-origin policy_ **and** its response
* has a JavaScript-related `Content-type`, the content of the `responseText`
* property will automatically be passed to `eval`.
*
* In other words: you don't even need to provide a callback to leverage
* pure-JavaScript Ajax responses. This is the convention that drives Rails's
* RJS.
*
* The list of JavaScript-related MIME-types handled by Prototype is:
*
* * `application/ecmascript`
* * `application/javascript`
* * `application/x-ecmascript`
* * `application/x-javascript`
* * `text/ecmascript`
* * `text/javascript`
* * `text/x-ecmascript`
* * `text/x-javascript`
*
* The MIME-type string is examined in a case-insensitive manner.
*
* ##### Methods you may find useful
*
* Instances of the [[Ajax.Request]] object provide several methods that come
* in handy in your callback functions, especially once the request is complete.
*
* ###### Is the response a successful one?
*
* The [[Ajax.Request#success]] method examines the XHR object's `status`
* property and follows general HTTP guidelines: unknown status is deemed
* successful, as is the whole `2xy` status code family. It's a generally
* better way of testing your response than the usual
* `200 == transport.status`.
*
* ###### Getting HTTP response headers
*
* While you can obtain response headers from the XHR object using its
* `getResponseHeader` method, this makes for verbose code, and several
* implementations raise an exception when the header is not found. To make
* this easier, you can use the [[Ajax.Response#getHeader]] method, which
* delegates to the longer version and returns `null` if an exception occurs:
*
* new Ajax.Request('/your/url', {
* onSuccess: function(response) {
* // Note how we brace against null values
* if ((response.getHeader('Server') || '').match(/Apache/))
* ++gApacheCount;
* // Remainder of the code
* }
* });
*
* ##### Evaluating JSON headers
*
* Some backends will return JSON not as response text, but in the `X-JSON`
* header. In this case, you don't even need to evaluate the returned JSON
* yourself, as Prototype automatically does so. It passes the result as the
* `headerJSON` property of the [[Ajax.Response]] object. Note that if there
* is no such header — or its contents are invalid — `headerJSON`
* will be set to `null`.
*
* new Ajax.Request('/your/url', {
* onSuccess: function(transport) {
* transport.headerJSON
* }
* });
**/
Ajax.Request = Class.create(Ajax.Base, {
_complete: false,
/**
* new Ajax.Request(url[, options])
* - url (String): The URL to fetch. When the _same-origin_ policy is in
* effect (as it is in most cases), `url` **must** be a relative URL or an
* absolute URL that starts with a slash (i.e., it must not begin with
* `http`).
* - options (Object): Configuration for the request. See the
* [[Ajax section]] for more information.
*
* Creates a new `Ajax.Request`.
**/
initialize: function($super, url, options) {
$super(options);
this.transport = Ajax.getTransport();
this.request(url);
},
request: function(url) {
this.url = url;
this.method = this.options.method;
var params = Object.clone(this.options.parameters);
if (!['get', 'post'].include(this.method)) {
// simulate other verbs over post
params['_method'] = this.method;
this.method = 'post';
}
this.parameters = params;
if (params = Object.toQueryString(params)) {
// when GET, append parameters to URL
if (this.method == 'get')
this.url += (this.url.include('?') ? '&' : '?') + params;
else if (/Konqueror|Safari|KHTML/.test(navigator.userAgent))
params += '&_=';
}
try {
var response = new Ajax.Response(this);
if (this.options.onCreate) this.options.onCreate(response);
Ajax.Responders.dispatch('onCreate', this, response);
this.transport.open(this.method.toUpperCase(), this.url,
this.options.asynchronous);
if (this.options.asynchronous) this.respondToReadyState.bind(this).defer(1);
this.transport.onreadystatechange = this.onStateChange.bind(this);
this.setRequestHeaders();
this.body = this.method == 'post' ? (this.options.postBody || params) : null;
this.transport.send(this.body);
/* Force Firefox to handle ready state 4 for synchronous requests */
if (!this.options.asynchronous && this.transport.overrideMimeType)
this.onStateChange();
}
catch (e) {
this.dispatchException(e);
}
},
onStateChange: function() {
var readyState = this.transport.readyState;
if (readyState > 1 && !((readyState == 4) && this._complete))
this.respondToReadyState(this.transport.readyState);
},
setRequestHeaders: function() {
var headers = {
'X-Requested-With': 'XMLHttpRequest',
'X-Prototype-Version': Prototype.Version,
'Accept': 'text/javascript, text/html, application/xml, text/xml, */*'
};
if (this.method == 'post') {
headers['Content-type'] = this.options.contentType +
(this.options.encoding ? '; charset=' + this.options.encoding : '');
/* Force "Connection: close" for older Mozilla browsers to work
* around a bug where XMLHttpRequest sends an incorrect
* Content-length header. See Mozilla Bugzilla #246651.
*/
if (this.transport.overrideMimeType &&
(navigator.userAgent.match(/Gecko\/(\d{4})/) || [0,2005])[1] < 2005)
headers['Connection'] = 'close';
}
// user-defined headers
if (typeof this.options.requestHeaders == 'object') {
var extras = this.options.requestHeaders;
if (Object.isFunction(extras.push))
for (var i = 0, length = extras.length; i < length; i += 2)
headers[extras[i]] = extras[i+1];
else
$H(extras).each(function(pair) { headers[pair.key] = pair.value });
}
for (var name in headers)
this.transport.setRequestHeader(name, headers[name]);
},
/**
* Ajax.Request#success() -> Boolean
*
* Tests whether the request was successful.
**/
success: function() {
var status = this.getStatus();
return !status || (status >= 200 && status < 300);
},
getStatus: function() {
try {
return this.transport.status || 0;
} catch (e) { return 0 }
},
respondToReadyState: function(readyState) {
var state = Ajax.Request.Events[readyState], response = new Ajax.Response(this);
if (state == 'Complete') {
try {
this._complete = true;
(this.options['on' + response.status]
|| this.options['on' + (this.success() ? 'Success' : 'Failure')]
|| Prototype.emptyFunction)(response, response.headerJSON);
} catch (e) {
this.dispatchException(e);
}
var contentType = response.getHeader('Content-type');
if (this.options.evalJS == 'force'
|| (this.options.evalJS && this.isSameOrigin() && contentType
&& contentType.match(/^\s*(text|application)\/(x-)?(java|ecma)script(;.*)?\s*$/i)))
this.evalResponse();
}
try {
(this.options['on' + state] || Prototype.emptyFunction)(response, response.headerJSON);
Ajax.Responders.dispatch('on' + state, this, response, response.headerJSON);
} catch (e) {
this.dispatchException(e);
}
if (state == 'Complete') {
// avoid memory leak in MSIE: clean up
this.transport.onreadystatechange = Prototype.emptyFunction;
}
},
isSameOrigin: function() {
var m = this.url.match(/^\s*https?:\/\/[^\/]*/);
return !m || (m[0] == '#{protocol}//#{domain}#{port}'.interpolate({
protocol: location.protocol,
domain: document.domain,
port: location.port ? ':' + location.port : ''
}));
},
/**
* Ajax.Request#getHeader(name) -> String | null
* - name (String): The name of an HTTP header that may have been part of
* the response.
*
* Returns the value of the given response header, or `null` if that header
* was not found.
**/
getHeader: function(name) {
try {
return this.transport.getResponseHeader(name) || null;
} catch (e) { return null; }
},
evalResponse: function() {
try {
return eval((this.transport.responseText || '').unfilterJSON());
} catch (e) {
this.dispatchException(e);
}
},
dispatchException: function(exception) {
(this.options.onException || Prototype.emptyFunction)(this, exception);
Ajax.Responders.dispatch('onException', this, exception);
}
});
Ajax.Request.Events =
['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];