NodeJS REPL Terminal: The Node JS terminal is also known as REPL Terminal/ Console and it is as same as the IDLE terminal of Python. To test a simple Node.js code the REPL terminal is used.
NodeJS REPL Terminal
In Node JS REPL Terminal, the R stands for Read, E stands for Eval, P stands for Print and L stands for Loop.
- R-Read: It just read the user’s input and parses the input into the javascript data structure and stores it into memory.
- E-Eval: To evaluates the javascript data structure.
- P-Print: To print the evaluated data structure result.
- L-Loop: Loops the command line until the 8user gives Ctrl+c(used to exit REPL Console).
If you can use the console on chrome then the REFL console in node js is also easy because both work the same.
To open the console in windows (command prompt) or Mac/Linux (terminal) use the following command.
C:\>node
NodeJS REPL Examples
Numeric Example
C:\>node >200+100 300 >
String Example
To concatenate two string you can use the ” +” operator.
> "Hello" + "World!" 'Hello World!' >
Variables Example
> var x=150, y=100 >x+y 250 >
Functions or Multiline Expression
If you want to provide functions or multiline Expression then use the “Enter” key. The REFL terminal in Node JS specifies three dots(…) to continue on the next line.
Functions or Multiline Expression Example
>function addNum(a,b){
... return a+b;
...}
undefined
>addNum(40,50)
90
>
External Javascript file
You can execute an external Javascript file just by specifying filename with node keyword command. Let’s take an example which is already created a file named as example.js that contains a string “Hello World!”.
C:\ node example.js Hello World! >
Exit REPL Terminal
To exit from the REFL terminal, double click on Ctrl+c.
> (To exit, press ^C again or type .exit) > C:\>
NodeJS REPL Commands
Let’s see some random REPL commands that are very useful to operate on REFL terminal Console.
| REPL Commands | Description |
|---|---|
| tab keys | It displays all the commands |
| .help | it displays help on commands |
| .break | Used to exit from the multiline expression |
| .clear | Used to exit from the multiline expression |
| .save filename | Saves the current node REPL session in the file |
| .load filename | Loads the given file in the current node REPL session. |
| Up/Down Keys | To know the previous commands in REPL. |
| ctrl+c | To exit from the current command. |
| Ctrl+c (double click) | To exit from the REPL terminal. |
The REPL terminal/console is a suitable platform to practice the basic examples in the node.js. To run simple examples like operators, data types, etc you can use REPL console.