cordova-plugin-migrate-localstorage/README.md

Migrate LocalStorage data from UIWebView to WKWebView

# Migrate LocalStorage

This plugin can be used in conjunction with
[cordova-plugin-wkwebview-engine](https://github.com/apache/cordova-plugin-wkwebview-engine)
to persist LocalStorage data when migrating from `UIWebView` to `WKWebView`. All related
files will be copied over automatically during startup so the user can simply pick up where they
left of.

## How to use

Simply add the plugin to your cordova project via the cli:
```sh
cordoa plugin add cordova-plugin-migrate-localstorage
```

## Notes

- LocalStorage files are only copied over once and only if no LocalStorage data exists for `WKWebView`
yet. This means that if you've run your app with `WKWebView` before this plugin will likely not work.
To test if data is migrated over correctly:
    1. Delete the app from your emulator or device
    2. Remove the `cordova-plugin-wkwebview-engine` and `cordova-plugin-migrate-localstorage` plugins
    3. Run your app and store some data in LocalStorage
    4. Add both plugins back
    5. Run your app again. Your data should still be there!

- Once the data is copied over, it is not being synced back to `UIWebView` so any changes done in
`WKWebView` will not persist should you ever move back to `UIWebView`. If you have a problem with this,
let us know in the issues section!

## Background

One of the drawbacks of migrating Cordova apps to `WKWebView` is that LocalStorage data does
not persist between the two. Unfortunately,
[cordova-plugin-wkwebview-engine](https://github.com/apache/cordova-plugin-wkwebview-engine)
does not offer a solution for this out of the box (see
https://issues.apache.org/jira/browse/CB-11974?jql=project%20%3D%20CB%20AND%20labels%20%3D%20wkwebview-known-issues).