定时器开启，清除

    var backgroundColor =["red", "yellow", "green"];
    var x = 0;
    //(颜色0.5秒切换背景)
    function switchBackground() {
        x++;
        x=x%3;         //         超过2则取余数，保证循环在0、1、2之间
        $(".designChange").css("background",backgroundColor[x])
    }


    //判断顶部工单信息在设计变更中是否存在该工单，存在则显示此按钮
    function checkIsDesignChange(){
        //获取工单编号
        var workSheetCode = $("#workSheetCode").val().substring(0,7);
        //清除定时器
		window.clearInterval(window.t);
        $.ajax({
            dataType:"json",
            type:"post",
            data:{"workSheetCode":workSheetCode},
            url:"${pageContext.request.contextPath}/C11/checkIsDesignChange",
            success:function(data){

                if(data=="success"){
                    //定时器
                    window.t = window.setInterval("switchBackground()","500");
                }else {
                    //去掉定时器的方法
                    window.clearInterval(window.t);
                    //去掉背景色
                    $(".designChange").css("background-color","transparent");
                }

            }
        })



    }