Each Weixin Mini Program has its own local cache. You can read, write, and clear the local cache via wx.setStorage/wx.setStorageSync, wx.getStorage/wx.getStorageSync, wx.clearStorage/wx.clearStorageSync, and wx.removeStorage/wx.removeStorageSync.
The storage limit of a Mini Program is 10 MB for a Weixin user. Storage is isolated based on users. On the same device, user A cannot read the data of user B. A Mini Program's user cannot read or write data of another Mini Program.
Local cache files are erased only when the code package is erased.