[robobun]

Problem

• Seven output lines on docs/runtime/repl.mdx are never what bun repl prints. Four show undefined after a declaration or an import. The others show single-quoted strings and a one-line { a: 1, b: 2 }.
• The examples omit the stack frames of an error and show > where a terminal shows ❯. The banner (v1.3.3) is older than the native REPL (v1.3.10).
• Other statements do not hold on main. Examples: __dirname is "", Ctrl+T swaps around the cursor, and a signal loses the history.

Fix

• Each example is now the exact screen of a pty session on a build of main (1.4.4-canary.1+0c864a07c).
• Three examples printed a long or changing result: a star count, a Response, the zod exports. Lines with a short, fixed result replace them.
• Twelve statements are corrected or scoped. Notes lists each with the run that decides it.
• Verified: a script types every example into a pty and compares the screen. All 9 match.

Background

• The prompt is ❯ in a terminal with colors. It is > with NO_COLOR=1 or without a terminal.
• The REPL rewrites each input. A declaration becomes an assignment, and the REPL prints its value.
• Open PRs repair the REPL defects behind some statements: repl: read __dirname and __filename from the globals #43487, repl: append each history entry to the history file when it is accepted #46109, Report a loop turn's rejections before the loop-alive check, and keep the exit code when an 'exit' listener throws #42032, repl: recognize regex literals and comments in continuation detection #37327, repl: clear the typed line on Ctrl+C in every mode, evaluate it on Ctrl+D in editor mode #46083. The new text says what main does, in words that stay true after them. repl: append each history entry to the history file when it is accepted #46109 rewrites the History paragraph.
• Line 32 (JSX) is unchanged. repl: import the JSX runtime for JSX input #46105 makes it hold.

Notes

How the page was checked

• Binary: the canary build of main, 1.4.4-canary.1+0c864a07c. src/runtime/cli/repl.rs, repl_command.rs and src/js_parser/repl_transforms.rs are the same at the head of this branch. A build of 367d939d9 (1.4.3) prints the same text, except the version in the banner.
• Interactive examples: typed key by key into bun repl in a pty (TERM=xterm-256color, NO_COLOR not set), one fresh session and one empty HOME for each block. The rendered screen must equal the block, line for line.
• -e and -p examples: run through sh, with stdout compared to the # lines.
• Statements: each sentence and each table row was run in the plain case and in the corner cases listed below.
• The page compiles as MDX and passes prettier --check.

Example lines that changed, and what the binary prints

Page on main	bun repl
Welcome to Bun v1.3.3	Welcome to Bun v1.4.4
> const greeting = "Hello, Bun!" gives undefined	"Hello, Bun!"
> greeting gives 'Hello, Bun!'	"Hello, Bun!"
JSON.parse("oops") gives one line	the message, two at lines, and an empty line
the star count 81234	96328 on the day of the check
const response = await fetch(...) gives undefined	the whole Response, 31 lines with dates and request ids
import { z } from "zod" gives undefined	the module namespace, 1096 lines with zod 4.6.7
const path = require("path") gives undefined	the path module, 37 lines
'/tmp/file.txt'	"/tmp/file.txt"
.save ./my-session.txt gives no output	Session saved to ./my-session.txt
-p "{ a: 1, b: 2 }" gives { a: 1, b: 2 }	four lines, one property on each line

Statements that changed, and the run behind each one

Statement on main	On the binary
__dirname and __filename are "resolved relative to your current working directory", as require and module are	__dirname prints "" and __filename prints "[repl]". After process.chdir(), require("./x.js") still loads the file of the directory that the REPL started in.
The two special variables "update after each evaluation"	_ does not change after a result of undefined. _error does not change after an input that does not throw.
_ is "the result of the last expression"	5, then undefined, then _ prints 5.
_error is "the last error that was thrown"	A throw in a setTimeout callback and a rejection that nothing awaits print an error and leave _error.
Unclosed brackets, braces, or parentheses continue on the next line	Also an unclosed ', " or backtick.
.editor "buffers all input" until Ctrl+D	A line that you typed and did not end with Enter is not evaluated. It stays on the next prompt.
.history prints "the command history"	With 1000 entries it prints entries 981 to 1000.
.copy copies to the clipboard	It writes ESC ] 52 ; c ; <base64> BEL. The terminal does the rest.
Ctrl+D exits "if line is empty"	On an empty ... line it does nothing. In editor mode it evaluates.
Ctrl+T swaps "the two characters before the cursor"	he█llo becomes hle█lo. At the end of the line it swaps the last two.
The REPL "automatically saves history"	Saved after .exit, Ctrl+D, and Ctrl+C twice. Not saved after SIGTERM, SIGHUP, SIGINT, SIGKILL, or process.exit(0). The limit holds: a file of 1500 lines plus one new entry leaves 1000 lines.
"On error, the process exits with code 1"	Exit 1 for a throw, a syntax error, and a rejected top-level await. Exit 0 for Promise.reject(new Error("x")) that nothing awaits, and for an async function that rejects and that nothing awaits.

Sentences that are new

• "The REPL prints the result of each input. A variable declaration prints the value of its last initializer." let a = 1, b = 2 prints 2. const { p } = { p: 1 } prints the object.
• "With NO_COLOR=1, or when standard input or standard output is not a terminal, the prompt is >." Each of the three conditions was run on its own.
• The OSC 52 sentence below the commands table.

Corner cases that the page does not describe

They are defects or limits of the REPL. None makes a sentence of the new page false in the plain case.

• The REPL parses input as TSX. <T>(x: T) => x and <number>5 are syntax errors, and <T,>(x: T) => x works. This belongs to line 32.
• An input that starts with { and is not an object literal runs without the REPL transform. { 40 + 2 } prints 42 and leaves _. An await in it is a syntax error. bun repl -p "{ console.log(1) } 42" exits 1. repl: evaluate input the REPL transform does not take through each caller's result path (-e/-p exit code, .copy, _) #45267 covers this path.
• A line that starts with . is read as a REPL command, also on a ... line: .5 + 1 prints Unknown command: .5.
• A bracket or a quote in a comment or in a regular expression counts as unclosed (REPL doesn't know how to handle regex literals #37326, repl: recognize regex literals and comments in continuation detection #37327).
• A multi-line entry comes back as one entry for each line in the next session (repl: keep multi-line history entries on one line of the history file #38023).
• Ctrl+C on a ... line and Ctrl+D in editor mode leave the text of the current line on the next prompt (repl: clear the typed line on Ctrl+C in every mode, evaluate it on Ctrl+D in editor mode #46083).
• Two sessions that are open at once: the last one to exit writes the file, and the entries of the other one are lost.
• The inline suggestion that a color terminal shows after the cursor is not on the page. Tab, Right, End, Ctrl+E and Ctrl+F accept it.
• A re-run import or require returns the module that is already loaded, also after the file changed.

Other open PRs that edit this page

• repl: append each history entry to the history file when it is accepted #46109 rewrites the History paragraph for its new behavior. It conflicts with this PR on that paragraph only. The text of repl: append each history entry to the history file when it is accepted #46109 is the right one once the REPL writes each entry when you enter it.
• repl: run --preload / -r / --require / --import before the first evaluation #46160 and repl: read non-terminal stdin as lines of text and take bracketed pastes as text #46248 add sections and merge with this branch without a conflict. Their new example blocks use > and Welcome to Bun v1.3.3. For repl: read non-terminal stdin as lines of text and take bracketed pastes as text #46248 the > is correct: the block shows piped input.
• repl: run sloppy sync input as script statements, not inside an arrow function #46104 changes the wrapper that the REPL puts around an input with no await. The two at lines in the special variables example come from that wrapper.

Hosts

The fetch examples use https://bun.com, as 7 other examples in docs/ do. https://example.com does not resolve in the environment where the examples were run, so a line with that host could not be run as written.

---

no test proof · iteration 0 · docs-only change; test-proof not applicable

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[robobun]

^{Updated 1:15 AM PT - Oct 21st, 2026}

✅ @robobun, your commit 5ad8958d2eeff13f93a10d6ba3cbd085280ad086 passed in Build #129990! 🎉

---

🧪   To try this PR locally:

bunx bun-pr 46308

That installs a local version of the PR into your bun-46308 executable, so you can run:

bun-46308 --bun

[robobun]

Status

Reproduced on main (1.4.4-canary.1+0c864a07c) and on 1.4.3:

printf 'const greeting = "Hello, Bun!"\ngreeting\n.exit\n' | NO_COLOR=1 bun repl
# the page on main: undefined, then 'Hello, Bun!'
# bun repl:         "Hello, Bun!", then "Hello, Bun!"

bun repl -p "{ a: 1, b: 2 }"
# the page on main: { a: 1, b: 2 }
# bun repl:         four lines, one property on each line

printf '__dirname\n__filename\n.exit\n' | NO_COLOR=1 bun repl
# the page on main: both resolve from the working directory
# bun repl:         "" and "[repl]"

With this PR, each of the 9 examples on the page equals the screen of a pty session on that build, line for line.

[claude]

Code review found no issues

No high-confidence issues detected in this change.