Use custom javascript / third party javascript inside a provider

hello,

im having a problem to use custom javascript / a third party javascript library inside a provider! how do i realize that?

the javascript file is not listed in the npm repository, so this seems not to work: https://mhartington.io/post/ionic2-external-libraries/

this solutions seems to work inside page but not inside a provider: https://stackoverflow.com/questions/43833895/how-to-include-js-file-in-ionic-3

best regards