Application Design _ How to trigger Auto Save Textarea Contents

Question

I wish to implement autosave functionality for textarea to IndexedDB for my winjs application.

How to trigger the same .

Either through 1. Eventlistener - It will be heavy if i save/update for each userinput.

                        2. Timer - In Desktop apps this is the way i followed in my apps. Starting timer in eventlistener when user inputs.

                          For Winjs what is the suggested way of doing  the same.

  

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gk