Bring the Phonegap app to the fore

I'm developing an HTML5 phone conversation app (which will be installed on both Andriod and iOS) and wondering how can I bring my app to the foreground after the user has switched to another app?

For example, there is a new notification coming from the server, and I want to activate my application and bring it to the front for the user's attention (just like someone calls you on Viber, your screen splashes with a call screen)

Thanks everyone in advance!