deno repl, interactive scripting prompt

deno repl [OPTIONS] [-- [ARGS]...]

Options Jump to heading#

--cert Jump to heading#

Load certificate authority from PEM encoded file.

--config Jump to heading#

Short flag: -c

Configure different aspects of deno including TypeScript, linting, and code formatting Typically the configuration file will be called deno.json or deno.jsonc and automatically detected; in that case this flag is not necessary.

--env-file Jump to heading#

Load environment variables from local file Only the first environment variable with a given key is used. Existing process environment variables are not overwritten.

--eval Jump to heading#

Evaluates the provided code when the REPL starts.

--eval-file Jump to heading#

Evaluates the provided file(s) as scripts when the REPL starts. Accepts file paths and URLs.

--location Jump to heading#

Value of globalThis.location used by some web APIs.

--no-config Jump to heading#

Disable automatic loading of the configuration file.

--seed Jump to heading#

Set the random number generator seed.

--v8-flags Jump to heading#

To see a list of all available flags use --v8-flags=--help Flags can also be set via the DENO_V8_FLAGS environment variable. Any flags set with this flag are appended after the DENO_V8_FLAGS environment variable.

Dependency management options Jump to heading#

--cached-only Jump to heading#

Require that remote dependencies are already cached.

--frozen Jump to heading#

Error out if lockfile is out of date.

--import-map Jump to heading#

Load import map file from local file or remote URL.

--lock Jump to heading#

Check the specified lock file. (If value is not provided, defaults to "./deno.lock").

--no-lock Jump to heading#

Disable auto discovery of the lock file.

--no-npm Jump to heading#

Do not resolve npm modules.

--no-remote Jump to heading#

Do not resolve remote modules.

--node-modules-dir Jump to heading#

Sets the node modules management mode for npm packages.

--reload Jump to heading#

Short flag: -r

Reload source code cache (recompile TypeScript) no value Reload everything jsr:@std/http/file-server,jsr:@std/assert/assert-equals Reloads specific modules npm: Reload all npm modules npm:chalk Reload specific npm module.

--vendor Jump to heading#

Toggles local vendor folder usage for remote modules and a node_modules folder for npm packages.

Debugging options Jump to heading#

--inspect Jump to heading#

Activate inspector on host:port [default: 127.0.0.1:9229]

--inspect-brk Jump to heading#

Activate inspector on host:port, wait for debugger to connect and break at the start of user script.

--inspect-wait Jump to heading#

Activate inspector on host:port and wait for debugger to connect before running user code.

Special variables Jump to heading#

The REPL provides a couple of special variables, that are always available:

Deno 1.14.3
exit using ctrl+d or close()
> "hello world!"
"hello world!"
> _
"hello world!"
> const foo = "bar";
undefined
> _
undefined

Special functions Jump to heading#

The REPL provides several functions in the global scope:

--eval flag Jump to heading#

--eval flag allows you to run some code in the runtime before you are dropped into the REPL. This is useful for importing some code you commonly use in the REPL, or modifying the runtime in some way:

$ deno repl --allow-net --eval 'import { assert } from "jsr:@std/assert@1"'
Deno 1.45.3
exit using ctrl+d, ctrl+c, or close()
> assert(true)
undefined
> assert(false)
Uncaught AssertionError
    at assert (https://jsr.io/@std/assert/1.0.0/assert.ts:21:11)
    at <anonymous>:1:22

--eval-file flag Jump to heading#

--eval-file flag allows you to run code from specified files before you are dropped into the REPL. Like the --eval flag, this is useful for importing code you commonly use in the REPL, or modifying the runtime in some way.

Files can be specified as paths or URLs. URL files are cached and can be reloaded via the --reload flag.

If --eval is also specified, then --eval-file files are run before the --eval code.

$ deno repl --eval-file=https://docs.deno.com/examples/welcome.ts,https://docs.deno.com/examples/local.ts
Download https://docs.deno.com/examples/welcome.ts
Welcome to Deno!
Download https://docs.deno.com/examples/local.ts
Deno 1.45.3
exit using ctrl+d or close()
> local // this variable is defined locally in local.ts, but not exported
"This is a local variable inside of local.ts"

Relative Import Path Resolution Jump to heading#

If --eval-file specifies a code file that contains relative imports, then the runtime will try to resolve the imports relative to the current working directory. It will not try to resolve them relative to the code file's location. This can cause "Module not found" errors when --eval-file is used with module files:

$ deno repl --eval-file=https://jsr.io/@std/encoding/1.0.0/ascii85.ts
error in --eval-file file https://jsr.io/@std/encoding/1.0.0/ascii85.ts. Uncaught TypeError: Module not found "file:///home/_validate_binary_like.ts".
    at async <anonymous>:2:13
Deno 1.45.3
exit using ctrl+d or close()
>

Tab completions Jump to heading#

Tab completions are crucial feature for quick navigation in REPL. After hitting tab key, Deno will now show a list of all possible completions.

$ deno repl
Deno 1.45.3
exit using ctrl+d or close()
> Deno.read
readTextFile      readFile          readDirSync       readLinkSync      readAll           read
readTextFileSync  readFileSync      readDir           readLink          readAllSync       readSync

Keyboard shortcuts Jump to heading#

DENO_REPL_HISTORY Jump to heading#

You can use DENO_REPL_HISTORY environmental variable to control where Deno stores the REPL history file. You can set it to an empty value, Deno will not store the history file.