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The Standard Library has been moved to JSR. See the blog post for details.

Deno Standard Modules


These modules do not have external dependencies and they are reviewed by the Deno core team. The intention is to have a standard set of high quality code that all Deno projects can use fearlessly.

Contributions are welcome!


Standard library is currently tagged independently of Deno version. This will change once the library is stabilized.

To check compatibility of different version of standard library with Deno CLI see this list.

How to use

These modules will eventually be tagged in accordance with Deno releases but as of today we do not yet consider them stable and so we version the standard modules differently from the Deno runtime to reflect this.

It is strongly recommended that you link to tagged releases to avoid unintended updates and breaking changes.

Don’t link to / import any module whose path:

  • Has a name or parent with an underscore prefix: _foo.ts, _util/bar.ts.
  • Is that of a test module or test data: test.ts, foo_test.ts, testdata/bar.txt.

Don’t import any symbol with an underscore prefix: export function _baz() {}.

These elements are not considered part of the public API, thus no stability is guaranteed for them.


To browse documentation for modules:


NOTE: This repository was unarchived and synced on Feb, 1st, 2021. If you already had it cloned, we suggest to do a fresh clone to avoid git conflicts.

deno_std is a loose port of Go’s standard library. When in doubt, simply port Go’s source code, documentation, and tests. There are many times when the nature of JavaScript, TypeScript, or Deno itself justifies diverging from Go, but if possible we want to leverage the energy that went into building Go. We generally welcome direct ports of Go’s code.

Please ensure the copyright headers cite the code’s origin.

Follow the style guide.

Opening a pull request

After cloning don’t forget to git submodule update --init.

Before opening a PR make sure to:

  • have the latest Deno version installed locally
  • add tests that cover your changes.
  • deno task test passes.
  • deno fmt --check passes.
  • deno task lint passes.

Give the PR a descriptive title.

Examples of good titles:

  • fix(http): Fix race condition in server
  • docs(fmt): Update docstrings
  • feat(log): Handle nested messages

Examples of bad titles:

  • fix #7123
  • update docs
  • fix bugs

Ensure there is a related issue and it is referenced in the PR text.

For contributions to the Node compatibility library please check the std/node contributing guide

About CI checks:

We currently have 9 checks on CI. Each PR should pass all of these checks to be accepted.

  • test with Deno canary on Windows
  • test with Deno canary on Linux
  • test with Deno canary on macOS
  • test Node polyfill with Deno canary on Windows
  • test Node polyfill with Deno canary on Linux
  • test Node polyfill with Deno canary on macOS
  • lint
  • wasm crypto check
  • CLA

For maintainers:

To release a new version a tag in the form of x.y.z should be added.

Internal Assertions

All internal non-test code, that is files that do not have test or bench in the name, must use the assertion functions within _utils/asserts.ts and not testing/asserts.ts. This is to create a separation of concerns between internal and testing assertions.