Working with Node.js REPL

1. Starting REPL Session

Command	Purpose
`node`	Start REPL
`node -i -e "code"`	Run code then drop into REPL
`NODE_REPL_HISTORY=~/.node_history`	Persist history across sessions

Input	Result
`1 + 2`	`3`
`const x = 5`	`undefined` (declaration)
`await fetch("https://api.example.com")`	Top-level await supported v18+

> .editor
// Entering editor mode (Ctrl+D to finish, Ctrl+C to cancel)
function add(a, b) {
  return a + b;
}
^D
> add(2, 3)
5

Key	Action
`Ctrl+D`	Finish input
`Ctrl+C`	Cancel

> 2 + 3
5
> _ * 2
10
> throw new Error("oops")
> _error.message
"oops"

Variable	Holds
`_`	Last evaluated value
`_error`	Last uncaught error

Setting	Effect
`util.inspect.defaultOptions.depth = null`	Unlimited depth
`util.inspect(obj, { colors: true })`	Colorized output
`console.dir(obj, { depth: 4 })`	Custom depth

> .load ./helpers.js
// All top-level declarations now available

Command	Action
`.load <file>`	Read file and execute line by line

Command	Action
`.save session.js`	Write history to file
`.load session.js`	Replay later

Command	Action
`.clear`	Reset REPL context (alias for `.break` in older versions)

Command	Purpose
`.help`	List all REPL commands
`.exit` / `Ctrl+D`	Quit REPL
`.break` / `Ctrl+C`	Abort current multi-line input
`.editor`	Multi-line editor mode