How to import a external javascript library

I have a node MCU Esp8266 and am looking at buying a

CANADUINO LCD 1602 2x16 Matrix Character Display - with Backlight - I2C Interface Included

I want to know what the steps are to importing this library
so I can use it with my MCU. There is this post on doing it Using I2C module with LCD 16x02 but I am not sure what the actual steps are to importing the library.

Any help would be great Thanks

You can fork that library and modify it’s mos.yml to support ESP8266:

platforms: [ esp32, esp8266 ]