refactor: improve device interface types (#996)

app/assets/javascripts/Device/WebDevice.ts

@@ -0,0 +1,26 @@
+import { Environment, RawKeychainValue } from '@standardnotes/snjs'
+import { WebOrDesktopDevice } from '@/Device/WebOrDesktopDevice'
+
+const KEYCHAIN_STORAGE_KEY = 'keychain'
+
+export class WebDevice extends WebOrDesktopDevice {
+  environment = Environment.Web
+
+  async getKeychainValue(): Promise<RawKeychainValue> {
+    const value = localStorage.getItem(KEYCHAIN_STORAGE_KEY)
+
+    if (value) {
+      return JSON.parse(value)
+    }
+
+    return {}
+  }
+
+  async setKeychainValue(value: RawKeychainValue): Promise<void> {
+    localStorage.setItem(KEYCHAIN_STORAGE_KEY, JSON.stringify(value))
+  }
+
+  async clearRawKeychainValue(): Promise<void> {
+    localStorage.removeItem(KEYCHAIN_STORAGE_KEY)
+  }
+}