Deno Standard Library

High-quality APIs for Deno and the web. Use fearlessly.

NOTE: The standard library is also available on JSR - check out the @std scope on JSR here.

Get Started

import { copy } from "https://deno.land/std@$STD_VERSION/fs/copy.ts";

await copy("./foo", "./bar");

See here for recommended usage patterns.

Documentation

Check out the documentation here.

Recommended Usage

1. Include the version of the library in the import specifier.

   Good:

   import { copy } from "https://deno.land/std@$STD_VERSION/fs/copy.ts";

2. Only import modules that you require.

   Bad (when using only one function):

   import * as fs from "https://deno.land/std@$STD_VERSION/fs/mod.ts";

   Good (when using only one function):

   import { copy } from "https://deno.land/std@$STD_VERSION/fs/copy.ts";

   Good (when using multiple functions):

   import * as fs from "https://deno.land/std@$STD_VERSION/fs/mod.ts";

3. Do not import symbols with a name prefixed by an underscore (they're not intended for public use).

   Bad:

   import { _format } from "https://deno.land/std@$STD_VERSION/path/_common/format.ts";

4. Do not import modules with a directory or filename prefixed by an underscore (they're not intended for public use).

   Bad:

   import { createLPS } from "https://deno.land/std@$STD_VERSION/streams/_common.ts";

   Good:

   import { TextLineStream } from "https://deno.land/std@$STD_VERSION/streams/text_line_stream.ts";

5. Do not import test modules or test data.

   Bad:

   import { test } from "https://deno.land/std@$STD_VERSION/front_matter/test.ts";

Packages

For a package to reach v1 (aka stable) status, it must meet the following requirements:

1. Approved by four members of the internal team. There must be consensus that the API design is satisfactory and unlikely to change in the future.
2. 100% documented, passing deno doc --lint checks and adhering to the documentation guidelines.
3. Maximum possible test coverage
4. No open issues or pull requests that might lead to breaking changes. For example, issues that suggest new non-breaking features are fine to exist at stabilization.

Package	Status	Latest version
archive	Unstable
assert	Settled
async	Settled
bytes	Settled
cli	Unstable
collections	Settled
console	Unstable
crypto	Settled
csv	Settled
data_structures	Unstable
datetime	Unstable
dotenv	Unstable
encoding	Settled
expect	Unstable
flags	Deprecated
fmt	Settled
front_matter	Settled
fs	Settled
html	Unstable
http	Unstable
ini	Unstable
io	Unstable
json	Settled
jsonc	Settled
log	Unstable
media_types	Settled
msgpack	Unstable
net	Unstable
path	Settled
permissions	Deprecated
regexp	Unstable
semver	Unstable
streams	Settled
testing	Settled
text	Unstable
toml	Settled
ulid	Unstable
url	Unstable
uuid	Settled
webgpu	Unstable
yaml	Settled

Note: Settled status means a package is unlikely to have breaking changes, but has not yet achieved v1 status.

Architecture

Check out the architecture guide here.

Design

Minimal Exports

Files are structured to minimize the number of dependencies they incur and the amount of effort required to manage them, both for the maintainer and the user. In most cases, only a single function or class, alongside its related types, are exported. In other cases, functions that incur negligible dependency overhead will be grouped together in the same file.

Deprecation Policy

We deprecate the APIs in the Standard Library when they get covered by new JavaScript language APIs or new Web Standard APIs. These APIs are usually removed after 3 minor versions.

If you still need to use such APIs after the removal for some reason (for example, the usage in Fresh island), please use the URL pinned to the version where they are still available.

For example, if you want to keep using readableStreamFromIterable, which was deprecated and removed in favor of ReadableStream.from in v0.195.0, please use the import URL pinned to v0.194.0:

import { readableStreamFromIterable } from "https://deno.land/std@0.194.0/streams/readable_stream_from_iterable.ts";

Contributing

Check out the contributing guidelines here.

Releases

The Standard Library is versioned independently of the Deno CLI. This will change once the Standard Library is stabilized. See here for the compatibility of different versions of the Deno Standard Library and the Deno CLI.

A new minor version of the Standard Library is published at the same time as every new version of the Deno CLI (including patch versions).

Badge

<a href="https://deno.land/std">
  <img
    width="135"
    height="20"
    src="https://raw.githubusercontent.com/denoland/deno_std/main/badge.svg"
    alt="Built with the Deno Standard Library"
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</a>

[![Built with the Deno Standard Library](https://raw.githubusercontent.com/denoland/deno_std/main/badge.svg)](https://deno.land/std)