Making a search query for MongoDB

I'm working on a website using EJS, Nodejs, and MongoDB. I have a search bar in one webpage where the user should be able to query the database based on any of the field names.I don't know how to use my input event listener (which is in a separate js file) to send a request to my api with the input object. I'm open to suggestions for as to how to approach what I'm trying to achieve.