应用场景：全站ajax，按钮提交

1.设置全局变量方式

<span style="font-size:14px;">var  ajaxSubmit ={};
    var   ajaxUrl = url; 
     ajaxSubmit[ajaxUrl] = function(){};
    if(!ajaxSubmit[ajaxUrl])
{
     ajaxSubmit[ajaxUrl].call(this);
}else
{
   xmlhttp.abort();
}</span>

ps：随时补充