Constnium/node_modules/eslint-plugin-import/docs/rules/namespace.md

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2022-06-23 02:27:43 +02:00
# import/namespace
Enforces names exist at the time they are dereferenced, when imported as a full namespace (i.e. `import * as foo from './foo'; foo.bar();` will report if `bar` is not exported by `./foo`.).
Will report at the import declaration if there are _no_ exported names found.
Also, will report for computed references (i.e. `foo["bar"]()`).
Reports on assignment to a member of an imported namespace.
Note: for packages, the plugin will find exported names
from [`jsnext:main`], if present in `package.json`.
Redux's npm module includes this key, and thereby is lintable, for example.
A module path that is [ignored] or not [unambiguously an ES module] will not be reported when imported.
[ignored]: ../README.md#importignore
[unambiguously an ES module]: https://github.com/bmeck/UnambiguousJavaScriptGrammar
## Rule Details
Currently, this rule does not check for possible
redefinition of the namespace in an intermediate scope. Adherence to the ESLint
`no-shadow` rule for namespaces will prevent this from being a problem.
For [ES7], reports if an exported namespace would be empty (no names exported from the referenced module.)
Given:
```js
// @module ./named-exports
export const a = 1
const b = 2
export { b }
const c = 3
export { c as d }
export class ExportedClass { }
// ES7
export * as deep from './deep'
```
and:
```js
// @module ./deep
export const e = "MC2"
```
See what is valid and reported:
```js
// @module ./foo
import * as names from './named-exports'
function great() {
return names.a + names.b // so great https://youtu.be/ei7mb8UxEl8
}
function notGreat() {
doSomethingWith(names.c) // Reported: 'c' not found in imported namespace 'names'.
const { a, b, c } = names // also reported, only for 'c'
}
// also tunnels through re-exported namespaces!
function deepTrouble() {
doSomethingWith(names.deep.e) // fine
doSomethingWith(names.deep.f) // Reported: 'f' not found in deeply imported namespace 'names.deep'.
}
```
### Options
#### `allowComputed`
Defaults to `false`. When false, will report the following:
```js
/*eslint import/namespace: [2, { allowComputed: false }]*/
import * as a from './a'
function f(x) {
return a[x] // Unable to validate computed reference to imported namespace 'a'.
}
```
When set to `true`, the above computed namespace member reference is allowed, but
still can't be statically analyzed any further.
## Further Reading
- Lee Byron's [ES7] export proposal
- [`import/ignore`] setting
- [`jsnext:main`](Rollup)
[ES7]: https://github.com/leebyron/ecmascript-more-export-from
[`import/ignore`]: ../../README.md#importignore
[`jsnext:main`]: https://github.com/rollup/rollup/wiki/jsnext:main