npm i https://github.com/Nenino2/Danfojs-type-declarations.git -D
https://github.com/opensource9ja/danfojs
To do that, you should use this tsconfig configuration: https://www.typescriptlang.org/docs/handbook/declaration-files/dts-from-js.html
Wrap the code into
declare module 'danfojs' {
...
}