Adding file://. permission to chrome extension

Question

How can I enable permissions for file:/// using chrome extensions. In my manifest.json I have tried:

"permissions": [
  "file:///*"
]

and

"permissions": [
  "file://*"
]

as well as

"permissions": [
  "*:///C"
]

None of these work.

Answer 1

"permissions": [
    "file://*/*"
]

Unless the extension is loaded from your local disk, file access will be disabled by default. The user has to manually approve this permission by visiting chrome://extensions/ and put a tick at the "Allow access to file URLs" checkbox.

In your code, you can see whether file access is allowed using chrome.extension.isAllowedFileSchemeAccess.

For a user-friendly way of requesting this access, see this answer.