eslint-plugin-import
This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, and prevent issues with misspelling of file paths and import names. All the goodness that the ES2015+ static module syntax intends to provide, marked up in your editor.
IF YOU ARE USING THIS WITH SUBLIME: see the bottom section for important info.
Rules
Static analysis:
- Ensure imports point to a file/module that can be resolved. (
no-unresolved
) - Ensure named imports correspond to a named export in the remote file. (
named
) - Ensure a default export is present, given a default import. (
default
) - Ensure imported namespaces contain dereferenced properties as they are dereferenced. (
namespace
) - Restrict which files can be imported in a given folder (
no-restricted-paths
) - Forbid import of modules using absolute paths (
no-absolute-path
) - Forbid
require()
calls with expressions (no-dynamic-require
) - Prevent importing the submodules of other modules (
no-internal-modules
) - Forbid Webpack loader syntax in imports (
no-webpack-loader-syntax
)
Helpful warnings:
Module systems:
- Report potentially ambiguous parse goal (
script
vs. module
) (unambiguous
) - Report CommonJS
require
calls and module.exports
or exports.*
. (no-commonjs
) - Report AMD
require
and define
calls. (no-amd
) - No Node.js builtin modules. (
no-nodejs-modules
)
Style guide:
Installation
npm install eslint-plugin-import -g
or if you manage ESLint as a dev dependency:
npm install eslint-plugin-import --save-dev
All rules are off by default. However, you may configure them manually
in your .eslintrc.(yml|json|js)
, or extend one of the canned configs:
---
extends:
- eslint:recommended
- plugin:import/errors
- plugin:import/warnings
plugins:
- import
rules:
import/no-unresolved: [2, {commonjs: true, amd: true}]
import/named: 2
import/namespace: 2
import/default: 2
import/export: 2
Resolvers
With the advent of module bundlers and the current state of modules and module
syntax specs, it's not always obvious where import x from 'module'
should look
to find the file behind module
.
Up through v0.10ish, this plugin has directly used substack's resolve
plugin,
which implements Node's import behavior. This works pretty well in most cases.
However, Webpack allows a number of things in import module source strings that
Node does not, such as loaders (import 'file!./whatever'
) and a number of
aliasing schemes, such as externals
: mapping a module id to a global name at
runtime (allowing some modules to be included more traditionally via script tags).
In the interest of supporting both of these, v0.11 introduces resolvers.
Currently Node and Webpack resolution have been implemented, but the
resolvers are just npm packages, so third party packages are supported (and encouraged!).
You can reference resolvers in several ways(in order of precedence):
- as a conventional
eslint-import-resolver
name, like eslint-import-resolver-foo
:
settings:
import/resolver: foo
module.exports = {
settings: {
'import/resolver': {
foo: { someConfig: value }
}
}
}
- with a full npm module name, like
my-awesome-npm-module
:
settings:
import/resolver: 'my-awesome-npm-module'
module.exports = {
settings: {
'import/resolver': {
'my-awesome-npm-module': { someConfig: value }
}
}
}
- with a filesystem path to resolver, defined in this example as a
computed property
name:
module.exports = {
settings: {
'import/resolver': {
[path.resolve('../../../my-resolver')]: { someConfig: value }
}
}
}
Relative paths will be resolved relative to the source's nearest package.json
or
the process's current working directory if no package.json
is found.
If you are interesting in writing a resolver, see the spec for more details.
Settings
You may set the following settings in your .eslintrc
:
import/extensions
A list of file extensions that will be parsed as modules and inspected for
export
s.
This defaults to ['.js']
, unless you are using the react
shared config,
in which case it is specified as ['.js', '.jsx']
.
Note that this is different from (and likely a subset of) any import/resolver
extensions settings, which may include .json
, .coffee
, etc. which will still
factor into the no-unresolved
rule.
Also, the following import/ignore
patterns will overrule this list.
import/ignore
A list of regex strings that, if matched by a path, will
not report the matching module if no export
s are found.
In practice, this means rules other than no-unresolved
will not report on any
import
s with (absolute filesystem) paths matching this pattern.
no-unresolved
has its own ignore
setting.
settings:
import/ignore:
- \.coffee$
- \.(scss|less|css)$
import/core-modules
An array of additional modules to consider as "core" modules--modules that should
be considered resolved but have no path on the filesystem. Your resolver may
already define some of these (for example, the Node resolver knows about fs
and
path
), so you need not redefine those.
For example, Electron exposes an electron
module:
import 'electron'
that would otherwise be unresolved. To avoid this, you may provide electron
as a
core module:
settings:
import/core-modules: [ electron ]
In Electron's specific case, there is a shared config named electron
that specifies this for you.
Contribution of more such shared configs for other platforms are welcome!
import/external-module-folders
An array of folders. Resolved modules only from those folders will be considered as "external". By default - ["node_modules"]
. Makes sense if you have configured your path or webpack to handle your internal paths differently and want to considered modules from some folders, for example bower_components
or jspm_modules
, as "external".
import/parsers
A map from parsers to file extension arrays. If a file extension is matched, the
dependency parser will require and use the map key as the parser instead of the
configured ESLint parser. This is useful if you're inter-op-ing with TypeScript
directly using Webpack, for example:
settings:
import/parsers:
typescript-eslint-parser: [ .ts, .tsx ]
In this case, typescript-eslint-parser
must be installed and require-able from
the running eslint
module's location (i.e., install it as a peer of ESLint).
This is currently only tested with typescript-eslint-parser
but should theoretically
work with any moderately ESTree-compliant parser.
It's difficult to say how well various plugin features will be supported, too,
depending on how far down the rabbit hole goes. Submit an issue if you find strange
behavior beyond here, but steel your heart against the likely outcome of closing
with wontfix
.
import/resolver
See resolvers.
import/cache
Settings for cache behavior. Memoization is used at various levels to avoid the copious amount of fs.statSync
/module parse calls required to correctly report errors.
For normal eslint
console runs, the cache lifetime is irrelevant, as we can strongly assume that files should not be changing during the lifetime of the linter process (and thus, the cache in memory)
For long-lasting processes, like eslint_d
or eslint-loader
, however, it's important that there be some notion of staleness.
If you never use eslint_d
or eslint-loader
, you may set the cache lifetime to Infinity
and everything should be fine:
settings:
import/cache:
lifetime: ∞
Otherwise, set some integer, and cache entries will be evicted after that many seconds have elapsed:
settings:
import/cache:
lifetime: 5
SublimeLinter-eslint
SublimeLinter-eslint introduced a change to support .eslintignore
files
which altered the way file paths are passed to ESLint when linting during editing.
This change sends a relative path instead of the absolute path to the file (as ESLint
normally provides), which can make it impossible for this plugin to resolve dependencies
on the filesystem.
This workaround should no longer be necessary with the release of ESLint 2.0, when
.eslintignore
will be updated to work more like a .gitignore
, which should
support proper ignoring of absolute paths via --stdin-filename
.
In the meantime, see roadhump/SublimeLinter-eslint#58
for more details and discussion, but essentially, you may find you need to add the following
SublimeLinter
config to your Sublime project file:
{
"folders":
[
{
"path": "code"
}
],
"SublimeLinter":
{
"linters":
{
"eslint":
{
"chdir": "${project}/code"
}
}
}
}
Note that ${project}/code
matches the code
provided at folders[0].path
.
The purpose of the chdir
setting, in this case, is to set the working directory
from which ESLint is executed to be the same as the directory on which SublimeLinter-eslint
bases the relative path it provides.
See the SublimeLinter docs on chdir
for more information, in case this does not work with your project.
If you are not using .eslintignore
, or don't have a Sublime project file, you can also
do the following via a .sublimelinterrc
file in some ancestor directory of your
code:
{
"linters": {
"eslint": {
"args": ["--stdin-filename", "@"]
}
}
}
I also found that I needed to set rc_search_limit
to null
, which removes the file
hierarchy search limit when looking up the directory tree for .sublimelinterrc
:
In Package Settings / SublimeLinter / User Settings:
{
"user": {
"rc_search_limit": null
}
}
I believe this defaults to 3
, so you may not need to alter it depending on your
project folder max depth.