title: How permanent is local storage on Android and iOS?
body: <p>When my app stores data locally on a phone, how permanent is that storage? I'll elaborate the exact situation:</p>
  
  <p>I'm building an app with jQueryMobile and Phonegap. It's essentially a browser app, but using Phonegap lets me package it and sell it in the app stores, among other advantages.</p>
  
  <p>Phonegap offers two ways of storage, both of which functions harmonize native functions of iOs, Android, Blackberry and some other OSs: localStorage (which is primitive key-value pairs), and a Web SQL database. 
  Both localStorage and web SQL are forms of storage that belong to the browser. Having said that, I can't find out how long the data will stay stored, under what circumstances it will be deleted, under what circumstances it may not be available, etc.</p>
  
  <p>For example, if the app stores data with localStorage or web SQL, and the user switches to a different standard browser on their Android, will the app be opened with the new browser and does that mean that the stored data is unavailable?</p>
  
  <p>If the user doesn't use the app for a year (which in my case is a realistic and not necessarily a bad scenario), will the data have expired like a cookie, or maybe been pushed out of the browser's storage by a deluge of data from other apps?</p>
  
  <p>Or will the data be destroyed even earlier, such as when:
  - user visits another site in the browser
  - browser is manually closed
  - browser process is killed or dies
  - etc</p>
  
  <p>Or are localStorage and web SQL the kind of storage that you only delete when (in Android) you go to Settings > Apps and actively remove the user data associated with the app?</p>
  
  <p>Thanks for any insights. There's nothing informative out there on ol' WWW.</p>
  
  <p>What happens in the case of app update. The local and web storage will get deleted or will it stay?</p>