NodeJS : Why does require('underscore') return undefined when executed at the node.js REPL?

To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

I have a hidden feature that I promised to tell you about.
This is a YouTube's feature which works on Desktop.
First, Make sure this video is playing.
Then, type the letters 'awesome' on the keyboard.
It will change your youtube progress bar into a flashing rainbow.

An introduction to myself in a few words,
Hello everyone, I'm Delphi.
Allow me to support you in answering your questions.
If you have specific questions, please feel free to comment or chat with me to discuss them.
Please feel free to leave a comment below if you have an answer or insights on the answer.
Providing an answer will be acknowledged and appreciated with a 'heart' from me.