Skip to main content
The deno repl command starts an interactive Read-Eval-Print Loop for evaluating JavaScript and TypeScript code.

​
Usage

deno repl [OPTIONS]
deno  # Starts REPL as default command

​
Description

The REPL provides an interactive environment to experiment with Deno, evaluate expressions, and test code snippets. It supports TypeScript, top-level await, and has built-in tab completion.

​
Flags

​
--eval-file
string
Evaluate a file before entering the REPL. Can be specified multiple times
​
--eval
string
Evaluate code before entering the REPL
​
--import-map
string
Load import map file
​
--no-npm
boolean
Do not resolve npm modules
​
--node-modules-dir
boolean
Enables or disables the use of a local node_modules folder
​
--config
string
Specify the configuration file
​
--no-config
boolean
Disable automatic loading of the configuration file

​
Permission Flags

By default, when running just deno (REPL as default command), all permissions are allowed. When explicitly running deno repl, you need to specify permissions:
​
--allow-read
string
Allow file system read access
​
--allow-write
string
Allow file system write access
​
--allow-net
string
Allow network access
​
--allow-env
string
Allow environment access
​
--allow-run
string
Allow running subprocesses
​
--allow-all
boolean
Allow all permissions

​
Features

​
TypeScript Support

The REPL natively supports TypeScript: 
> const greeting: string = "Hello, Deno!";
> console.log(greeting);
Hello, Deno!

​
Top-level Await

Use await at the top level: 
> const response = await fetch("https://api.github.com/users/denoland");
> const data = await response.json();
> data.name
"Deno"

​
Tab Completion

Press Tab to autocomplete: 
> console.l<Tab>
log    
info   
warn   
error

​
Special Variables

  • _ - Result of the last evaluated expression
  • _error - Last thrown error
> 2 + 2
4
> _ * 2
8

​
Multiline Input

Press Shift+Enter for multiline input: 
> function greet(name) {<Shift+Enter>
    return `Hello, ${name}!`;<Shift+Enter>
  }<Shift+Enter>
> greet("World")
"Hello, World!"

​
Examples

​
Basic REPL

Start the REPL with all permissions: 
deno

​
REPL with specific permissions

deno repl --allow-net --allow-read

​
Evaluate code on startup

Run code before entering the REPL: 
deno repl --eval "const API_URL = 'https://api.example.com'"

​
Load a file before REPL

Evaluate a file to set up the environment: 
deno repl --eval-file setup.ts

​
Load multiple files

deno repl --eval-file config.ts --eval-file utils.ts

​
With import map

deno repl --import-map=import_map.json

​
With configuration file

deno repl --config deno.json

​
Keyboard Shortcuts

  • Ctrl+C - Exit (press twice) or cancel current input
  • Ctrl+D - Exit
  • Tab - Autocomplete
  • Shift+Enter - Multiline input
  • Up/Down - Navigate command history
  • Ctrl+R - Reverse search history

​
REPL History

Command history is saved in:
  • Unix: ~/.cache/deno/repl_history.txt
  • Windows: %LOCALAPPDATA%/deno/repl_history.txt
  • macOS: ~/Library/Caches/deno/repl_history.txt

​
Exit the REPL

You can exit the REPL in several ways: 
// Type close() function
> close()

// Press Ctrl+D

// Press Ctrl+C twice

​
Tips

​
Import modules

> const { join } = await import("jsr:@std/path");
> join("foo", "bar")
"foo/bar"

​
Access Deno APIs

> Deno.version
{ deno: "2.1.0", v8: "12.9.202.5", typescript: "5.6.2" }

​
Quick experiments

Test regular expressions: 
> /\d+/.test("hello123")
true
Try out array methods: 
> [1, 2, 3, 4, 5].filter(x => x % 2 === 0)
[2, 4]

Build docs developers (and LLMs) love

Get started for freeTalk to us