js timestamp 转换 date

// json 时间格式转化 例如：1520305366000
function timeStamp2String(time){
???var datetime = new Date();
???datetime.setTime(time);
???var year = datetime.getFullYear();
???var month = datetime.getMonth() + 1 < 10 ? "0" + (datetime.getMonth() + 1) : datetime.getMonth() + 1;
???var date = datetime.getDate() < 10 ? "0" + datetime.getDate() : datetime.getDate();
???var hour = datetime.getHours()< 10 ? "0" + datetime.getHours() : datetime.getHours();
???var minute = datetime.getMinutes()< 10 ? "0" + datetime.getMinutes() : datetime.getMinutes();
???var second = datetime.getSeconds()< 10 ? "0" + datetime.getSeconds() : datetime.getSeconds();
???return year + "-" + month + "-" + date+“-”+hours+“-”+minutes+“-”+seconds;
}