Node.js - REPL Terminal
January 24th 2021 71

The node command is the one we use to run our Node.js scripts:
node script.js
If we omit the filename, we use it in REPL mode:
node
Note: REPL also known as Read Evaluate Print Loop is a programming language environment(Basically a console window) that takes single expression as user input and returns the result back to the console after execution.
If you try it now in your terminal
, this is what happens:
❯ node
>
the command stays in idle mode and waits for us to enter something.
Tip: if you are unsure how to open your terminal, google "How to open terminal on <your-operating-system>".
The REPL
is waiting for us to enter some JavaScript code, to be more precise.
Start simple and enter
> console.log('test')
test
undefined
>
The first value, test, is the output we told the console to print, then we get undefined which is the return value of running console.log()
.
We can now enter a new line of JavaScript.
REPL Commands
- ctrl + c − terminate the current command.
- ctrl + c twice − terminate the Node REPL.
- ctrl + d − terminate the Node REPL.
- Up/Down Keys − see command history and modify previous commands.
- tab Keys − list of current commands.
- .help − list of all commands.
- .break − exit from multiline expression.
- .clear − exit from multiline expression.
- .save filename − save the current Node REPL session to a file.
- .load filename − load file content in current Node REPL session.