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   }