Javascript获取页面来源(referer)

[code]
var getReferrer=function() {
var referrer = '';

try {
referrer = window.top.document.referrer;
} catch(e) {
if(window.parent) {
try {
referrer = window.parent.document.referrer;
} catch(e2) {
referrer = '';
}
}
}
if(referrer === '') {
referrer = document.referrer;
}
return referrer;
};[/code]