试试看

interface MyFile extends File {
    lastModified: any;
}

let myFile = <MyFile>originalFile;
let lm = myFile.lastModified;

也适用于lastModifiedDate，它已被弃用，但目前仍在Chrome中，并且是IE中的only option：

// use non-deprecated lastModified field instead 
new Date(file.lastModified)

// in-line type assertion
(file as unknown as { lastModifiedDate: Date }).lastModifiedDate

// type assertion with special type
type DateFile = File & {
  lastModifiedDate: Date;
};
...
(file as DateFile).lastModifiedDate

将通过使用lastModified或Assert它存在来防止TS2551 Property 'lastModifiedDate' does not exist on type 'File'. Did you mean 'lastModified'? ts(2551)错误。