js处理后端返回的不同文件的流

  var fileformData = new FormData();
            fileformData.append('file1',vm.fileListLeft[0].raw);
            fileformData.append('file2',vm.fileListRight[0].raw);
            axios.post(ctx + 'fire/drawing/compare',fileformData,{responseType: 'blob'}).then(function (res) {
                try{
                    parent.vm.compareLoading = false;
                }catch (e){
                    vm.compareLoading = false;
                }
                if (res.status === 200 && res.data) {
                    var disposition = res.headers['content-disposition'];
                    var contentType = res.headers['content-type'];
                    if(contentType.includes('json')){
                        var data = res.data;
                        var reader = new FileReader();
                        reader.onload = function () {
                            var errorInfos = JSON.parse(reader.result);
                            var msg = errorInfos.content;
                            try{
                                parent.vm.comparePdfShow = false;
                                parent.vm.compareLoading = false;
                            }catch (e){
                                vm.comparePdfShow = false;
                                vm.compareLoading = false;
                            }
                            vm.$message.error(msg||'操作失败，请稍后重试！');
                        }
                        reader.onerror = function (err) {
                            vm.$message.error('转换失败，请稍后重试！');
                        }
                        reader.readAsText(data);
                    }else{
                        try {
                            var fileName = decodeURI(disposition.substring(disposition.indexOf('filename=') + 9, disposition.length));
                            vm.fileType = vm.getFileType(fileName);
                            var blob = res.data;
                            var objectURL = window.URL.createObjectURL(blob);
                            if(vm.fileType == "pdf"){
                                try{
                                    parent.vm.fileType = "pdf";
                                    parent.vm.pdfUrl = ctx + 'fire/drawing/viewPdf.html?fileUrl='+objectURL;
                                }catch (e){
                                    vm.fileType = "pdf";
                                    vm.pdfUrl = ctx + 'fire/drawing/viewPdf.html?fileUrl='+objectURL;
                                }
                            }else{
                                try{
                                    parent.vm.imgUrl = ctx + 'fire/drawing/viewPic.html?objectURL='+objectURL+'&fileName='+fileName;
                                }catch (e){
                                    vm.imgUrl = ctx + 'fire/drawing/viewPic.html?objectURL='+objectURL+'&fileName='+fileName;
                                }
                            }
                        } catch (e) {
                            try{
                                parent.vm.comparePdfShow = false;
                                parent.vm.compareLoading = false;
                            }catch (e){
                                vm.comparePdfShow = false;
                                vm.compareLoading = false;
                            }
                            vm.$message.error(res.data.content||'操作失败，请稍后重试！');
                        }
                    }
                } else {// 其它情况
                    try{
                        parent.vm.comparePdfShow = false;
                        parent.vm.compareLoading = false;
                    }catch (e){}
                    vm.$message.error(res.data.content||'操作失败，请稍后重试！');
                }
            }).catch(function (error) {
                try{
                    parent.vm.comparePdfShow = false;
                    parent.vm.compareLoading = false;
                }catch (e){}
                vm.$message.error('对比出错，请稍后重试！');
            });