获取视频时长：

param.file:上传成功的文件

var url = URL.createObjectURL(param.file);
var audioElement = new Audio(url);
var duration=""
audioElement.addEventListener("loadedmetadata", function(_event) {
  duration = audioElement.duration; //时长为秒，小数
});

时长转换成时分秒显示：

value:时长， dateFormat:显示格式

getDuration(value,dateFormat){
  let hour = parseInt((value) / 3600);
  if (hour<10) {//时
    hour = "0" + hour;
  }
  var minute = parseInt((value % 3600) / 60);
    if (minute<10) {//分
        minute = "0" + minute;
    }
    var second = Math.ceil(value % 60);
    if (second<10) {//秒
        second = "0" + second;
    }
    switch (dateFormat) {
        case 'hh:mm':
          return hour + ":" + minute;
          break;
        case 'mm:ss':
          return minute + ":" + second;
          break;
        case 'hh':
          return hour;
          break;
        default:
          return hour + ":" + minute + ":" + second;
          break;
    }
}

成功！

OK，就这样，End~