Приведу реализацию ajax в JQuery, извините что полностью, просто очень хочется понять как она у них сделана.
Обратим внимание на
function complete() {
// Process result
if ( s.complete ) {
s.complete.call( callbackContext, xhr, status);
}
// The request was completed
if ( s.global ) {
trigger( "ajaxComplete", [xhr, s] );
}
// Handle the global AJAX counter
if ( s.global && ! --jQuery.active ) {
jQuery.event.trigger( "ajaxStop" );
}
}
Т.е. этот код запустится как только завершиться загрузка.
Можете, пожалуйста объяснить, что происходит внутри этого метода
ajax: function( origSettings ) {
var s = jQuery.extend(true, {}, jQuery.ajaxSettings, origSettings);
var jsonp, status, data,
callbackContext = origSettings && origSettings.context || s,
type = s.type.toUpperCase();
// convert data if not already a string
if ( s.data && s.processData && typeof s.data !== "string" ) {
s.data = jQuery.param( s.data, s.traditional );
}
// Handle JSONP Parameter Callbacks
if ( s.dataType === "jsonp" ) {
if ( type === "GET" ) {
if ( !jsre.test( s.url ) ) {
s.url += (rquery.test( s.url ) ? "&" : "?") + (s.jsonp || "callback") + "=?";
}
} else if ( !s.data || !jsre.test(s.data) ) {
s.data = (s.data ? s.data + "&" : "") + (s.jsonp || "callback") + "=?";
}
s.dataType = "json";
}
// Build temporary JSONP function
if ( s.dataType === "json" && (s.data && jsre.test(s.data) || jsre.test(s.url)) ) {
jsonp = s.jsonpCallback || ("jsonp" + jsc++);
// Replace the =? sequence both in the query string and the data
if ( s.data ) {
s.data = (s.data + "").replace(jsre, "=" + jsonp + "$1");
}
s.url = s.url.replace(jsre, "=" + jsonp + "$1");
// We need to make sure
// that a JSONP style response is executed properly
s.dataType = "script";
// Handle JSONP-style loading
window[ jsonp ] = window[ jsonp ] || function( tmp ) {
data = tmp;
success();
complete();
// Garbage collect
window[ jsonp ] = undefined;
try {
delete window[ jsonp ];
} catch(e) {}
if ( head ) {
head.removeChild( script );
}
};
}
if ( s.dataType === "script" && s.cache === null ) {
s.cache = false;
}
if ( s.cache === false && type === "GET" ) {
var ts = now();
// try replacing _= if it is there
var ret = s.url.replace(rts, "$1_=" + ts + "$2");
// if nothing was replaced, add timestamp to the end
s.url = ret + ((ret === s.url) ? (rquery.test(s.url) ? "&" : "?") + "_=" + ts : "");
}
// If data is available, append data to url for get requests
if ( s.data && type === "GET" ) {
s.url += (rquery.test(s.url) ? "&" : "?") + s.data;
}
// Watch for a new set of requests
if ( s.global && ! jQuery.active++ ) {
jQuery.event.trigger( "ajaxStart" );
}
// Matches an absolute URL, and saves the domain
var parts = rurl.exec( s.url ),
remote = parts && (parts[1] && parts[1] !== location.protocol || parts[2] !== location.host);
// If we're requesting a remote document
// and trying to load JSON or Script with a GET
if ( s.dataType === "script" && type === "GET" && remote ) {
var head = document.getElementsByTagName("head")[0] || document.documentElement;
var script = document.createElement("script");
script.src = s.url;
if ( s.scriptCharset ) {
script.charset = s.scriptCharset;
}
// Handle Script loading
if ( !jsonp ) {
var done = false;
// Attach handlers for all browsers
script.onload = script.onreadystatechange = function() {
if ( !done && (!this.readyState ||
this.readyState === "loaded" || this.readyState === "complete") ) {
done = true;
success();
complete();
// Handle memory leak in IE
script.onload = script.onreadystatechange = null;
if ( head && script.parentNode ) {
head.removeChild( script );
}
}
};
}
// Use insertBefore instead of appendChild to circumvent an IE6 bug.
// This arises when a base node is used (#2709 and #4378).
head.insertBefore( script, head.firstChild );
// We handle everything using the script element injection
return undefined;
}
var requestDone = false;
// Create the request object
var xhr = s.xhr();
if ( !xhr ) {
return;
}
// Open the socket
// Passing null username, generates a login popup on Opera (#2865)
if ( s.username ) {
xhr.open(type, s.url, s.async, s.username, s.password);
} else {
xhr.open(type, s.url, s.async);
}
// Need an extra try/catch for cross domain requests in Firefox 3
try {
// Set the correct header, if data is being sent
if ( s.data || origSettings && origSettings.contentType ) {
xhr.setRequestHeader("Content-Type", s.contentType);
}
// Set the If-Modified-Since and/or If-None-Match header, if in ifModified mode.
if ( s.ifModified ) {
if ( jQuery.lastModified[s.url] ) {
xhr.setRequestHeader("If-Modified-Since", jQuery.lastModified[s.url]);
}
if ( jQuery.etag[s.url] ) {
xhr.setRequestHeader("If-None-Match", jQuery.etag[s.url]);
}
}
// Set header so the called script knows that it's an XMLHttpRequest
// Only send the header if it's not a remote XHR
if ( !remote ) {
xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
}
// Set the Accepts header for the server, depending on the dataType
xhr.setRequestHeader("Accept", s.dataType && s.accepts[ s.dataType ] ?
s.accepts[ s.dataType ] + ", */*" :
s.accepts._default );
} catch(e) {}
// Allow custom headers/mimetypes and early abort
if ( s.beforeSend && s.beforeSend.call(callbackContext, xhr, s) === false ) {
// Handle the global AJAX counter
if ( s.global && ! --jQuery.active ) {
jQuery.event.trigger( "ajaxStop" );
}
// close opended socket
xhr.abort();
return false;
}
if ( s.global ) {
trigger("ajaxSend", [xhr, s]);
}
// Wait for a response to come back
var onreadystatechange = xhr.onreadystatechange = function( isTimeout ) {
// The request was aborted
if ( !xhr || xhr.readyState === 0 || isTimeout === "abort" ) {
// Opera doesn't call onreadystatechange before this point
// so we simulate the call
if ( !requestDone ) {
complete();
}
requestDone = true;
if ( xhr ) {
xhr.onreadystatechange = jQuery.noop;
}
// The transfer is complete and the data is available, or the request timed out
} else if ( !requestDone && xhr && (xhr.readyState === 4 || isTimeout === "timeout") ) {
requestDone = true;
xhr.onreadystatechange = jQuery.noop;
status = isTimeout === "timeout" ?
"timeout" :
!jQuery.httpSuccess( xhr ) ?
"error" :
s.ifModified && jQuery.httpNotModified( xhr, s.url ) ?
"notmodified" :
"success";
var errMsg;
if ( status === "success" ) {
// Watch for, and catch, XML document parse errors
try {
// process the data (runs the xml through httpData regardless of callback)
data = jQuery.httpData( xhr, s.dataType, s );
} catch(err) {
status = "parsererror";
errMsg = err;
}
}
// Make sure that the request was successful or notmodified
if ( status === "success" || status === "notmodified" ) {
// JSONP handles its own success callback
if ( !jsonp ) {
success();
}
} else {
jQuery.handleError(s, xhr, status, errMsg);
}
// Fire the complete handlers
complete();
if ( isTimeout === "timeout" ) {
xhr.abort();
}
// Stop memory leaks
if ( s.async ) {
xhr = null;
}
}
};
// Override the abort handler, if we can (IE doesn't allow it, but that's OK)
// Opera doesn't fire onreadystatechange at all on abort
try {
var oldAbort = xhr.abort;
xhr.abort = function() {
if ( xhr ) {
oldAbort.call( xhr );
}
onreadystatechange( "abort" );
};
} catch(e) { }
// Timeout checker
if ( s.async && s.timeout > 0 ) {
setTimeout(function() {
// Check to see if the request is still happening
if ( xhr && !requestDone ) {
onreadystatechange( "timeout" );
}
}, s.timeout);
}
// Send the data
try {
xhr.send( type === "POST" || type === "PUT" || type === "DELETE" ? s.data : null );
} catch(e) {
jQuery.handleError(s, xhr, null, e);
// Fire the complete handlers
complete();
}
// firefox 1.5 doesn't fire statechange for sync requests
if ( !s.async ) {
onreadystatechange();
}
function success() {
// If a local callback was specified, fire it and pass it the data
if ( s.success ) {
s.success.call( callbackContext, data, status, xhr );
}
// Fire the global callback
if ( s.global ) {
trigger( "ajaxSuccess", [xhr, s] );
}
}
function complete() {
// Process result
if ( s.complete ) {
s.complete.call( callbackContext, xhr, status);
}
// The request was completed
if ( s.global ) {
trigger( "ajaxComplete", [xhr, s] );
}
// Handle the global AJAX counter
if ( s.global && ! --jQuery.active ) {
jQuery.event.trigger( "ajaxStop" );
}
}
function trigger(type, args) {
(s.context ? jQuery(s.context) : jQuery.event).trigger(type, args);
}
// return XMLHttpRequest to allow aborting the request etc.
return xhr;
},
