Best solution for VIM auto-save?

Question

I like the kind that automatically saves every few seconds, like webstorm and Pycharm.
VIM I used :help 'autosave' and found the following help:

'autosave' 'as' number  (default 0)                                         
           ¦Automatically write the current buffer to file N seconds after the last change has been made and when 'modified' is still set.         
           ¦Default: 0 = do not autosave the buffer.                            
    Alternative: have 'autosave' use 'updatetime' and 'updatecount' but make    
    them save the file itself besides the swapfile. 

Then I added: set autosave as 5 in .vimrc, which means it will be automatically saved after 5 seconds of modification, but it prompted: Unknown option: autosave What happens?

Answer 1

The abbreviation of

let autosave=5，那个as是autosave is not a word 23333333333333333