;(function($) {
 function AjaxQueue(override) {
 this.override = !!override;
 };
 AjaxQueue.prototype = {
 requests: new Array(),
 offer: function(options) {
 var _self = this;
 var xhrOptions = $.extend({}, options, {
 complete: function(jqXHR, textStatus) {
 if($.isArray(options.complete)) {
 var funcs = options.complete;
 for(var i = 0, len = funcs.length; i < len; i++)
 funcs[i].call(this, jqXHR, textStatus);
 } else {
 if(options.complete)
 options.complete.call(this, jqXHR, textStatus);
 }
 _self.poll();
 },
 beforeSend: function(jqXHR, settings) {
 if(options.beforeSend)
 var ret = options.beforeSend.call(this, jqXHR, settings);
 if(ret === false) {
 _self.poll();
 return ret;
 }
 }
 });
 if(this.override) {
 this.replace(xhrOptions);
 } else {
 this.requests.push(xhrOptions);
 if(this.requests.length == 1) {
 $.ajax(xhrOptions);
 }
 }
 },
 replace: function(xhrOptions) {
 var prevRet = this.peek();
 if(prevRet != null) {
 prevRet.abort();
 }
 this.requests.shift();
 this.requests.push($.ajax(xhrOptions));
 },
 poll: function() {
 if(this.isEmpty()) {
 return null;
 }
 var processedRequest = this.requests.shift();
 var nextRequest = this.peek();
 if(nextRequest != null) {
 $.ajax(nextRequest);
 }
 return processedRequest;
 },
 peek: function() {
 if(this.isEmpty()) {
 return null;
 }
 var nextRequest = this.requests[0];
 return nextRequest;
 },
 isEmpty: function() {
 return this.requests.length == 0;
 }
 };
 var queue = {};
 var AjaxManager = {
 createQueue: function(name, override) {
 return queue[name] = new AjaxQueue(override);
 },
 destroyQueue: function(name) {
 if(queue[name]) {
 queue[name] = null;
 delete queue[name];
 }
 },
 getQueue: function(name) {
 return ( queue[name] ? queue[name] : null);
 }
 };
 $.AM = AjaxManager;
})(jQuery);
使用示例：
var newQueue = $.AM.createQueue(‘queue‘);
$(function(){
          newQueue.offer({url:‘?c=Message&m=write&a=10‘});
          newQueue.offer({url:‘?c=Message&m=write&a=10‘});
          newQueue.offer({url:‘?c=Message&m=write&a=1‘});
});

(function($) {
  
    var ajax = $.ajax,
        pendingRequests = {},
        synced = [],
        syncedData = [],
        ajaxRunning = [];
  
  
    $.ajax = function(settings) {
        // create settings for compatibility with ajaxSetup
        settings = jQuery.extend(settings, jQuery.extend({}, jQuery.ajaxSettings, settings));
  
        var port = settings.port;
  
        switch (settings.mode) {
            case "abort":
                if (pendingRequests[port]) {
                    pendingRequests[port].abort();
                }
                return pendingRequests[port] = ajax.apply(this, arguments);
            case "queue":
                var _old = settings.complete;
                settings.complete = function() {
                    if (_old) {
                        _old.apply(this, arguments);
                    }
                    if (jQuery([ajax]).queue("ajax" + port).length > 0) {
                        jQuery([ajax]).dequeue("ajax" + port);
                    } else {
                        ajaxRunning[port] = false;
                    }
                };
  
                jQuery([ajax]).queue("ajax" + port, function() {
                    ajax(settings);
                });
  
                if (jQuery([ajax]).queue("ajax" + port).length == 1 && !ajaxRunning[port]) {
                    ajaxRunning[port] = true;
                    jQuery([ajax]).dequeue("ajax" + port);
                }
  
                return;
            case "sync":
                var pos = synced.length;
  
                synced[pos] = {
                    error: settings.error,
                    success: settings.success,
                    complete: settings.complete,
                    done: false
                };
  
                syncedData[pos] = {
                    error: [],
                    success: [],
                    complete: []
                };
  
                settings.error = function() { syncedData[pos].error = arguments; };
                settings.success = function() { syncedData[pos].success = arguments; };
                settings.complete = function() {
                    syncedData[pos].complete = arguments;
                    synced[pos].done = true;
  
                    if (pos == 0 || !synced[pos - 1])
                        for (var i = pos; i < synced.length && synced[i].done; i++) {
                        if (synced[i].error) synced[i].error.apply(jQuery, syncedData[i].error);
                        if (synced[i].success) synced[i].success.apply(jQuery, syncedData[i].success);
                        if (synced[i].complete) synced[i].complete.apply(jQuery, syncedData[i].complete);
  
                        synced[i] = null;
                        syncedData[i] = null;
                    }
                };
        }
        return ajax.apply(this, arguments);
    };
  
})(jQuery);



(function(){
    $("body").queue([]);
    $("#dtitle").click(function(){
        $.ajax({
            url: "test.php?t=" + new Date().getMilliseconds(),
            success: function(html){
                jQuery("ul").append(html);
            },
            //用abort而不用queue，是因为需求是需要最后一个ajax request，而之前的ajax request
            //其实并没有用，那何必要等它们执行完呢？中途就可以把它中止掉
            mode: "abort"
        });
    });
});