jq禁止form多次提交

window.onload=function(){
    var form = $('form').get(0);
    if (form) {
    	flag=false;  //监听变量用于提交一次表单
	    form.onsubmit=function(e){
	        e.preventDefault();
	        if (flag) {return;};
	        flag=true;
	        setTimeout(function(){
	            form.submit();
	        },100)
	         
	    }
    }
}