Ext3中用于执行同步请求时，要引入此js文件，最好在ExtJS基本需要文件引入后，再引入此文件。-Ext3 used to perform the synchronization request, the introduction of the js file, preferably in the ExtJS after the introduction of the basic needs of the file, then the

富客户端应用下的extjs可用于同步执行的库函数。-Rich client applications can be used under the extjs library functions performed simultaneously.