js跳转导致获取来源地址document.referrer失败的解决方案

	var ref = "";
	if (document.referrer.length > 0) {  
 　　  ref = document.referrer;
　　}
	if (ref.length == 0 && opener.location.href.length > 0) {  
	 　ref = opener.location.href;
	}
	alert(ref)

更详细的document.referrer兼容性请参考：
https://blog.csdn.net/flyingpig2016/article/details/53130912