<script type="text/javascript">
//点击刷新验证码
function change_yzm(obj)
{
$(obj).attr('src','<?php echo site_url('login/yzm_img') ?>'+'/'+Math.random());
}
</script>
<div class="yzm_img" > <img src="<?php echo site_url('login/yzm_img') ?>" id="" title="点击刷新验证码" alt="点击刷新验证码" onclick="change_yzm(this)" /> </div>