Typescript: Property 'name' does not exist on type 'FormDataEntryValue'

Question

I have:

const file = formData.get('documents[]')

What type is file?

const file: FormDataEntryValue | null

I need to access to file?.name.

and i got:

Property 'name' does not exist on type 'FormDataEntryValue'.

Answer 1

FormDataEntryValue is defined as an union of File and string: type FormDataEntryValue = File | string;

Thus you need to check first that the variable is indeed a File:

if (file instanceof File) {
  console.log(file.name);
}