This is a starter prototype offlie youtube downloader using ionic 3 and youtubee v3 api with node js you have to run your own node js server with youtube api keys or find a api that can provide you serach string objects.
$ sudo npm install -g ionic cordova
$ ionic cordova platform add ios
$ ionic cordova run ios
to run server just do
node server.js
Substitute ios for android if not on a Mac.