Thinkphp with-verification code unintentional mistakes

First look at the code: 1 $ (". Verify_img"). Click (function () {2 var timenow = new Date (). GetTime (); 3 var url = "{: U (' Index/lo Ginverify ')}&t= "+timenow; 4 alert (URL); 5 $ (this). attr ("src", url) 6});   The above code causes the verification code click Switch to cause the CAPTCHA picture to be unable to display.         Then look at the following code: $ (". Reloadverify"). Click (function () {var timenow = new Date (). GetTime ();        var url = "{: U (' index/loginverify ')}?t=" +timenow; $ ("#image_d"). attr ("src", url)}; What is the area of the above code? and the difference between &. You can see where the problem is when you compare it. It is also effective to follow a random number directly behind a question mark. var url = "{: U (' index/loginverify ')}?"   +math.random (); It is clear that the question has been written here.