方法一：
var url = "http://blog.csdn.net/jungsagacity/article/details/7645580";
url = '/' + url.split('/').slice(3).join('/');
方法二：
var url = "http://blog.csdn.net/jungsagacity/article/details/7645580";
url = url.replace(/^http:\/\/[^/]+/, "");
方法三：
var a = document.createElement('A');a.href = 'http://blog.csdn.net/jungsagacity/article/details/7645580';
console.log(a.pathname)
