Read and write the contents of a textbox in a local web from a javascript program running in a console

I am running a program in a console written in javascript, I need to be able to read and update a text box in a local web page (that only runs on my computer). The program is a robot that is used in a Discord server. The process would be serious 1 read information in the text box 2 execute commands to interact with discord 3 update information from the text box