module: unflag detect-module · nodejs/node@9916458

* Strings passed in as an argument to `--eval`, or piped to `node` via `STDIN`,

with the flag `--input-type=module`.

* When using [`--experimental-detect-module`][], code containing syntax only

successfully parsed as [ES modules][], such as `import` or `export`

statements or `import.meta`, having no explicit marker of how it should be

interpreted. Explicit markers are `.mjs` or `.cjs` extensions, `package.json`

`"type"` fields with either `"module"` or `"commonjs"` values, or

`--input-type` or `--experimental-default-type` flags. Dynamic `import()`

expressions are supported in either CommonJS or ES modules and would not

cause a file to be treated as an ES module.

* Code containing syntax only successfully parsed as [ES modules][], such as

`import` or `export` statements or `import.meta`, with no explicit marker of

how it should be interpreted. Explicit markers are `.mjs` or `.cjs`

extensions, `package.json` `"type"` fields with either `"module"` or

`"commonjs"` values, or `--input-type` or `--experimental-default-type` flags.

Dynamic `import()` expressions are supported in either CommonJS or ES modules

and would not force a file to be treated as an ES module. See

[Syntax detection][].

Node.js will treat the following as [CommonJS][] when passed to `node` as the

initial input, or when referenced by `import` statements or `import()`

things easier for build tools and loaders to determine how the files in the

package should be interpreted.

### Syntax detection

<!-- YAML

added:

- v21.1.0

- v20.10.0

changes:

- version:

- REPLACEME

pr-url: https://github.com/nodejs/node/pull/53619

description: Syntax detection is enabled by default.

-->

> Stability: 1.2 - Release candidate

Node.js will inspect the source code of ambiguous input to determine whether it

contains ES module syntax; if such syntax is detected, the input will be treated

as an ES module.

Ambiguous input is defined as:

* Files with a `.js` extension or no extension; and either no controlling

`package.json` file or one that lacks a `type` field; and

`--experimental-default-type` is not specified.

* String input (`--eval` or STDIN) when neither `--input-type` nor

`--experimental-default-type` are specified.

ES module syntax is defined as syntax that would throw when evaluated as

CommonJS. This includes the following:

* `import` statements (but _not_ `import()` expressions, which are valid in

CommonJS).

* `export` statements.

* `import.meta` references.

* `await` at the top level of a module.

* Lexical redeclarations of the CommonJS wrapper variables (`require`, `module`,

`exports`, `__dirname`, `__filename`).

### Modules loaders

Node.js has two systems for resolving a specifier and loading modules.

[ES modules]: esm.md

[Node.js documentation for this section]: https://github.com/nodejs/node/blob/HEAD/doc/api/packages.md#conditions-definitions

[Runtime Keys]: https://runtime-keys.proposal.wintercg.org/

[Syntax detection]: #syntax-detection

[WinterCG]: https://wintercg.org/

[`"exports"`]: #exports

[`"imports"`]: #imports

[`"type"`]: #type

[`--conditions` / `-C` flag]: #resolving-user-conditions

[`--experimental-default-type`]: cli.md#--experimental-default-typetype

[`--experimental-detect-module`]: cli.md#--experimental-detect-module

[`--no-addons` flag]: cli.md#--no-addons

[`ERR_PACKAGE_PATH_NOT_EXPORTED`]: errors.md#err_package_path_not_exported

[`esm`]: https://github.com/standard-things/esm#readme