JavaWeb手机短信实现前台利用JS获取随机验证码，倒计时效果

var random="";
        function getMessages(button){
            //前台倒计时
            front(button);
            //请求后台发送验证码
            behind();
        }
        
        ///后台发送短信
        function behind (){
            //随机码
            random=getRandom();
            var tel=document.getElementById("tel").value;
            $.post("<%=path%>/sendSmsServlet.action",{tel:tel,random:random},function(data){
        
            });
        }
        
        //前台实现倒计时
        function front(button){
            //前台倒计时
            var count = 60;
            button.value = count + "s后可重新获取验证码";
            //将按钮设置为不可点击
            button.setAttribute("disabled", "disabled");
            var time = setInterval(function() {
                count--;
                button.value = count + "s后可重新获取验证码";
                if (count <= 0) {
                    //关闭定时器
                    clearInterval(time);
                    //改变按钮标题
                    button.value = "获取验证码";
                    button.removeAttribute("disabled");
                }
            }, 1000);
        }
        
        //获取四位随机完整码
        function getRandom(){
            var str="";
            for(var i=0;i<4;i++){
                var num=parseInt(Math.random()*1000000000%10);
                str+=num;
            }
            return str;
        }