vue 获取视频时长的实例代码

<el-upload class="upload-demo" :action="actionUrl" :show-file-list="false" :on-success="handleAvatarSuccess"
     :before-upload="beforeAvatarUpload">
     <button class="ce-button not-hover primary">
      <i class="ce-icon_upload"></i>
      <span>重新上传</span>
     </button>
    </el-upload>

 beforeAvatarUpload(file) {
    var fileName = file.name || ''
    var ext = fileName.split('.')[fileName.split('.').length - 1]
    if (ext !== "doc" && ext !== "docx" && ext !== "xls" && ext !== "xlsx"
     && ext !== "ppt" && ext !== "pptx" && ext !== "pdf" && ext !== "mp4") {
     this.$notify({
      title: "失败",
      message: "上传资源只能是 doc/docx/xls/xlsx/ppt/pptx/pdf/mp4 格式!",
      type: "error",
      duration: 3000
     });
     return false
    }
    // ppt(10MB)，word(10MB)，excel(5MB)
    if (ext == "doc" || ext == "docx" || ext == "ppt" || ext == "pptx") {
     debugger
     if (parseInt(file.size) > parseInt('10485760‬')) {
      this.$notify({
       title: "失败",
       message: "上传word、ppt文件上限为10MB!",
       type: "error",
       duration: 3000
      });
      return false
     }
    }
    if (ext == 'mp4') { // 获取视频时长
     var url = URL.createObjectURL(file);
     var audioElement = new Audio(url);
     var duration;
     audioElement.addEventListener("loadedmetadata", function (_event) {
      duration = audioElement.duration; //时长为秒，小数，182.36
      this.$parent.$data.wDuration = parseInt(duration)
      console.log(duration);
     });
    }
    this.$parent.$data.wFileName = file.name
    this.$parent.$data.wSize = parseFloat(file.size / 1024).toFixed(2) //获取文件大小
   }