How to implement a constant check of product availability?

Question

Node.js

There is a site with goods, it has an api for checking the goods, that is, whether the goods are on sale or not. How can I implement a constant check for many products in Node.js? That is, so that my bot constantly listens to this api and checks for the availability of goods, and as soon as the right one appears, let me know, or I will send a post request via api to buy the goods that have appeared. Will there be a big load if, say, I follow 50 products at once?
UPD
And how can you listen to an array of goods at once? Maybe someone has come across something similar.

Answer 1

Will you follow from different places? I would follow everyone at once through ws. When a product changes, a message is sent to update the product or array of products.