function test() {
            var arrstr = ['http://www.test.com/landing?m=xx&u=xx&t=xx', 'http://www.test.com/landing?u=xx&m=xx&t=xx', 'http://www.test.com?u=xx&m=xx&t=xx', '123.12.23.23?t=xx&m=xx&u=xx'];
            var reg = /^.+?\?(?:[tum][^&]+?&){2}[tum].+/g;
            for (var i = 0; i < arrstr.length; i++) {
                var str = arrstr[i];
               document.write(str.match(reg)+"<br/>");
            }
        }

------解决方案--------------------

var reg=/^(https?:\/\/)?.+?\?[mut]=.+(&[mut]=.+){2}$/;