js获取上下文路径

<script type="text/javascript">
			function login() {
				var username=$("#username").val();
                var password=$("#password").val();
                var path=getContextPath();
                alert(path)
                $.ajax({
					url:path+"/login",
					type:"post",
					data:{
					    "username":username,
						"password":password
						},
					dataType:"json",
					success:function () {
						alert("执行成功");
                    },
					error:function () {
						alert("执行失败");
                    }
            })

            }
            //获取上下文路径
            function getContextPath(){
                var pathName = document.location.pathname;
                var index = pathName.substr(1).indexOf("/");
                var result = pathName.substr(0,index+1);
                return result;
            }
		</script>