上传4个文件，通过文件悬停右端的删除键删除其中一个文件，然后提交，结果提交了4个文件

      <el-upload
        class="upload-demo"
        ref="upload"
        :action="uploadFileUrl"
        :on-remove="beforeRemove"
        multiple
        :limit="10"
        :on-exceed="handleExceed"
        :file-list="fileList"
        :auto-upload="false"
        :before-upload="beforeupload"
        :on-success="handleUploadSuccess"
        :headers="headers"
        :http-request="httpRequest"
        :on-change="handleChange"
        name="files"
      >
    //移除文件
    beforeRemove(file, fileList) {
      console.log("file,filelist", file, fileList);
      return this.$confirm(`确定移除 ${file.name}？`, "提示", {
        confirmButtonText: "确定",
        cancelButtonText: "取消",
        type: "warning",
      })
        .then(() => {
          // 去重，这块得把相同的url对比进行去除。要不然他是没有真正的删除。再次上传还是会出现之前删除的文件
          let fileIndex = this.fileList.findIndex(
            (item) => item.url == file.url
          );
          this.fileList.splice(fileIndex, 1);
        })
        .catch(() => {
          this.$message({
            type: "info",
            message: "已取消移除",
          });
        });
    },