PHP ajax基础

后台对数据处理，并返回前台：

<?php
//接收
$action = $_GET['action'];
if ($action == 'orderID') {

    $orderID = trim($_POST['orderID']);
    if($orderID != ""){
        $sql = "INSERT INTO `db`.`tb` (`id`, `orderID`, `add_time`) VALUES (NULL, '$orderID', '$time')";
        if (mysql_query($sql)) {
            echo "";
        }
    }    

}
?>

前台取值：

//文本框取值
var name = $("input[name='name']").val();

//radio 单选项取值
var list01 = $("input[name='list01']:checked").val();

//ajax
$.ajax({
            type: "POST",
            url: "question.php?action=orderID",
            dataType: "json",
            data: {"orderID":orderID},
            beforeSend: function(){
                console.log("loading...");
            },
            success: function(back){

                if(back==){
                    //location.reload();
                    console.log("ok");
                    step1.hide();
                    step2.fadeIn();

                }else{
                    console.log("no");
                }
            }
        });

//JS随机输出提示
var msgArr = new Array("请填完再提交哦！","还有没填完哦！","没填完就提交？还是检查下吧！","检查下，还是填完吧！","不能有空哦！");
var num = parseInt(Math.random() * msgArr.length);
var msg = msgArr[num];
alert(msg);