Ext.Ajax.request 同步

Ext.Ajax.request參數中並沒有同步這個參數，但是很多時候需要同步請求來提供Componnet中的資料，而且沒有add方法，比如 checkboxgroup 中動態check選項,所以應該修改Ext.Ajax.request真正的要求方法Ext.lib.Ajax.request
具體代碼來自EXT官方論壇：
Ext.lib.Ajax.request = function(method, uri, cb, data, options) {
    if(options){
        var hs = options.headers;
        if(hs){
            for(var h in hs){
                if(hs.hasOwnProperty(h)){
                    this.initHeader(h, hs[h], false);
                }
            }
        }
        if(options.xmlData){
            if (!hs || !hs['Content-Type']){
                this.initHeader('Content-Type', 'text/xml', false);
            }
            method = (method ? method : (options.method ? options.method : 'POST'));
            data = options.xmlData;
        }else if(options.jsonData){
            if (!hs || !hs['Content-Type']){
                this.initHeader('Content-Type', 'application/json', false);
            }
            method = (method ? method : (options.method ? options.method : 'POST'));
            data = typeof options.jsonData == 'object' ? Ext.encode(options.jsonData) : options.jsonData;
        }
    }

   return this["sync" in options ? "syncRequest" : "asyncRequest"](method, uri, cb, data);//這句制定調用的方法，如果sync傳遞了就調用syncRequest，否則調用原來的方法asyncRequest};

syncRequest方法如下：
Ext.lib.Ajax.syncRequest = function(method, uri, callback, postData)
{
    var o = this.getConnectionObject();

    if (!o) {
        return null;
    }
    else {
        o.conn.open(method, uri, false); 

        if (this.useDefaultXhrHeader) {
            if (!this.defaultHeaders['X-Requested-With']) {
                this.initHeader('X-Requested-With', this.defaultXhrHeader, true);
            }
        }

        if(postData && this.useDefaultHeader && (!this.hasHeaders || !this.headers['Content-Type'])){
            this.initHeader('Content-Type', this.defaultPostHeader);
        }

        if (this.hasDefaultHeaders || this.hasHeaders) {
            this.setHeader(o);
        }

        o.conn.send(postData || null);
        this.handleTransactionResponse(o, callback);
        return o;
    }
};

調用：
Ext.Ajax.request({
url:'',
scope:this,
sync:true,
success:function(){}
});