REPL, which stands for Read Eval Print Loop, is an interactive programming environment that allows you to execute JavaScript code in real-time. In NodeJS, the REPL functionality provides a command-line interface where you can type JavaScript code and see the results immediately.
What is REPL?
REPL, short for Read Eval Print Loop, is a programming environment that allows you to execute code interactively. It reads user input, evaluates it, prints the result, and then loops back to wait for more input. This interactive nature makes REPL well-suited for experimenting with code snippets, testing small pieces of code, and exploring language features.
Why Use REPL?
REPL is useful for various tasks, including:
- Quick Testing: You can quickly test JavaScript expressions and statements without needing to create a separate script file.
- Experimentation: REPL provides a sandbox environment where you can experiment with language features, try out new ideas, and interactively explore APIs.
- Debugging: You can use REPL for debugging purposes by evaluating expressions and inspecting variables in real-time.
How to Use REPL in NodeJS:
To start the NodeJS REPL, simply type node in your terminal and press Enter. You’ll enter the REPL mode, where you can type JavaScript code interactively. Here’s a basic example:
$ node
> 1 + 1
2
> let greeting = 'Hello, world!'
undefined
> console.log(greeting)
Hello, world!
undefined