Instructions need to include restart of 'ng serve'

[wgtthompson]

Spent about a day on this wondering why I had followed all directions but couldn't get it to work. I kept getting an error in the JS console in Firefox sayingERROR ReferenceError: Dygraph is not defined. The Dygraph object just showing a spinning bubble wheel in the browser. No amount of searching the internet for combinations of the error message, Angular, Dygraph, ng-dygraphs, etc came anywhere close to a solution. I branched out and started researching how to use an existing JS library within angular and after very careful reading I noticed one little statement that said you need to restart 'ng serve' in order for the modifications to angular.json (angular-cli.json in the instruction) to be picked up.

[pierre-fromager]

As provided in other issue comment I advise to add the following npm packages to your project.
@types/dygraphs
dygraphs
Then in your ts code do the import as below.
import Dygraph from 'dygraphs';