Import external javascript to Ionic

I am facing some problem when try to import javascript library to my Ionic app, specifically import this chart into my ionic project 

Firstly I install the latest ionic, after that go to


open the assets folder, create a


folder inside assets copy .js inside this js folder goto


Add path <script src="assets/js/N.js">
Go to typescript file and declare var N;

And another way like this video:

But both of them didn’t worked. Do you have any else idea ? Thank you.

does anyone have any ideas?