REPL

An interactive JavaScript and TypeScript REPL with syntax highlighting, history, and tab completion

bun repl starts an interactive Read-Eval-Print Loop (REPL) for evaluating JavaScript and TypeScript expressions. Use it to test code snippets, explore APIs, and debug.

terminal

bun repl

Welcome to Bun v1.3.3
Type .copy [code] to copy to clipboard. .help for more info.

> 1 + 1
2
> const greeting = "Hello, Bun!"
undefined
> greeting
'Hello, Bun!'

---

Features

• TypeScript & JSX — Write TypeScript and JSX directly. Bun transpiles everything on the fly.
• Top-level await — Await promises directly at the prompt without wrapping in an async function.
• Syntax highlighting — Input is highlighted as you type.
• Persistent history — History is saved to ~/.bun_repl_history and persists across sessions.
• Tab completion — Press Tab to complete property names and REPL commands.
• Multi-line input — Unclosed brackets, braces, and parentheses automatically continue on the next line.
• Node.js globals — require, module, __dirname, and __filename are available, resolved relative to your current working directory.

---

Special variables

The REPL exposes two special variables that update after each evaluation.

Variable	Description
_	The result of the last expression
_error	The last error that was thrown

> 2 + 2
4
> _ * 10
40
> JSON.parse("oops")
SyntaxError: JSON Parse error: Unexpected identifier "oops"
> _error
SyntaxError: JSON Parse error: Unexpected identifier "oops"

---

Top-level await

Promises are automatically awaited. You can await any expression directly at the prompt.

> await fetch("https://api.github.com/repos/oven-sh/bun").then(r => r.json()).then(r => r.stargazers_count)
81234
> const response = await fetch("https://example.com")
undefined
> response.status
200

---

Importing modules

Just like Bun’s runtime, you can use either require or import in the REPL and it Just Works — mix ESM and CommonJS freely at the prompt. Module resolution uses the same rules as bun run, so you can import from node_modules, relative paths, or node: builtins.

> import { z } from "zod"
undefined
> const path = require("path")
undefined
> z.string().parse(path.join("/tmp", "file.txt"))
'/tmp/file.txt'

Declarations persist for the rest of the session, and const/let can be redeclared across evaluations (unlike in regular scripts) so you can re-run import and require statements while iterating.

---

Multi-line input

When you press Enter on a line with unclosed brackets, braces, or parentheses, the REPL automatically continues on the next line. The prompt changes to ... to indicate continuation.

> function add(a, b) {
...   return a + b;
... }
undefined
> add(2, 3)
5

For longer multi-line entries, use .editor to enter editor mode, which buffers all input until you press Ctrl+D.

---

REPL commands

Type .help at the prompt to see all available REPL commands.

Command	Description
.help	Print the help message listing commands and keybindings
.exit	Exit the REPL
.clear	Clear the screen
.copy	Copy the last result to the clipboard. Pass an expression to evaluate and copy it: .copy 1 + 1
.load	Load a file into the REPL session: .load ./script.ts
.save	Save the current REPL history to a file: .save ./session.txt
.editor	Enter multi-line editor mode (press Ctrl+D to evaluate, Ctrl+C to cancel)
.break	Cancel the current multi-line input
.history	Print the command history

---

Keybindings

The REPL supports Emacs-style line editing.

Keybinding	Action
Ctrl+A	Move to start of line
Ctrl+E	Move to end of line
Ctrl+B / Ctrl+F	Move backward/forward one character
Alt+B / Alt+F	Move backward/forward one word
Ctrl+U	Delete to start of line
Ctrl+K	Delete to end of line
Ctrl+W	Delete word backward
Ctrl+D	Delete character (or exit if line is empty)
Ctrl+L	Clear screen
Ctrl+T	Swap the two characters before the cursor
Up / Down	Navigate history
Tab	Auto-complete
Ctrl+C	Cancel current input (press twice on empty line to exit)

---

History

REPL history is automatically saved to ~/.bun_repl_history (up to 1000 entries) and loaded at the start of each session. Use Up/Down to navigate.

To export your history to a different file, use .save:

> .save ./my-session.txt

---

Non-interactive mode

Use -e / --eval to evaluate a script with REPL semantics and exit. Use -p / --print to additionally print the result.

terminal

bun repl -e "const x: number = 42; console.log(x)"
# 42

bun repl -p "await fetch('https://example.com').then(r => r.status)"
# 200

bun repl -p "{ a: 1, b: 2 }"
# { a: 1, b: 2 }

This uses the same transforms as the interactive REPL, so a bare object literal like { a: 1 } is treated as an object expression instead of a block statement. The process exits after the event loop drains (pending timers and I/O complete first). On error, the process exits with code 1.