Rescuing data from offline sites

Accidentally a site has been down, for any reason like the domain changed or you're moving from an offline device, you'll find that the data in web storage is unreadable.

DevTools? Open a page like this:

This site can’t be reached - a.kkocdko.site unexpectedly closed the connection.

Type localStorage in DevTools "Console" tab:

> localStorage

Uncaught DOMException: Failed to read the 'localStorage' property from 'Window': Access is denied for this document. at <anonymous>:1:1

Chrome prevents you from accessing web storage if the server can't produce a valid response.

The solution is DevTools "Overrides" function. Switch to "Sources" tab, open "Overrides" panel, and select a folder. Recommend creating a new directory.

Because the server is down, you should create a folder named as current domain manually instead of some "create overrides" menu entry. Then create a blank index.html. Like this:

- overrides
  - a.kkocdko.site
    - index.html

Refresh and the blank page shown as expected. Now you can dump / restone storage using JSON.stringify(localStorage) and Object.assign(localStorage, xxx).

> localStorage

Storage {a: '1', length: 1}

Other ways

• Use service worker to respond.

• Read directly from Chromium's localStorage levelDB file.

• Run a local DNS or use hosts file to hijack the site.