How can I implement multi-tasks?

Question

Node.js

I welcome everyone!
I recently dived into the node, and I don’t understand much. For example, there is a script that sends requests to a specific API. Each request is one key, it is individual for each user, how can I implement it so that the keys are placed in the file first, and all the keys are sent at once? Not in turn, but precisely at one moment all at once. And does everyone have their own request? It is impossible to put all the data in one request at once