时间戳的差，时间戳转换时分秒，时分秒格式化

function eventProcessNodeTimeComputed (a, b) {
                let sdate = new Date(a);//结束时间
                let now = new Date(b);//开始时间
                let endTime=sdate.getTime();//结束时间
                let startTime=now.getTime();//开始时间
                let timeDiff =endTime  - startTime;
                let hours = parseInt((timeDiff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
                let minutes = parseInt((timeDiff % (1000 * 60 * 60)) / (1000 * 60));
                let seconds = (timeDiff % (1000 * 60)) / 1000;
                hours < 10 ? hours='0'+hours : hours; //小时格式化
                minutes < 10 ? minutes='0'+minutes : minutes; //分钟格式化
                seconds < 10 ? seconds='0'+seconds : seconds; //秒钟格式化
            
                let k=hours+':'+minutes+':'+seconds;
                // return k;
                if("0" > seconds){
                    return "--"
                }else{
                    return k;
                }
            };