eslint loader for webpack
$ npm install eslint-loader
In your webpack configuration
module.exports = {
// ...
module: {
loaders: [
{test: /\.js$/, loader: "eslint-loader", exclude: /node_modules/}
]
}
// ...
}
When using with transpiling loaders (like babel-loader
), make sure they are in correct order
(bottom to top). Otherwise files will be check after being processed by babel-loader
module.exports = {
// ...
module: {
loaders: [
{test: /\.js$/, loaders: [ "babel-loader", "eslint-loader" ], exclude: /node_modules/},
]
}
// ...
}
To be safe, you can use preLoaders
section to check source files, not modified
by other loaders (like babel-loader
)
module.exports = {
// ...
module: {
preLoaders: [
{test: /\.js$/, loader: "eslint-loader", exclude: /node_modules/}
]
}
// ...
}
You can pass eslint options directly by
- Adding a query string to the loader for this loader usage only
{
module: {
preLoaders: [
{
test: /\.js$/,
loader: "eslint-loader?{rules:{semi:0}}",
exclude: /node_modules/,
},
],
},
}
- Adding an
eslint
entry in your webpack config for global options:
module.exports = {
eslint: {
configFile: 'path/.eslintrc'
}
}
Note that you can use both methods in order to benefit from global & specific options
This option will enable ESLint autofix feature.
Be careful, this option might cause webpack to enter an infinite build loop if some issues cannot be fixed properly.
This option will enable caching of the linting results into a file. This is particullarly usefull to reduce linting time when doing full build.
The cache is writting inside the ./node_modules/.cache
directory, thanks to the usage
of the find-cache-dir module.
Loader accepts a function that will have one argument: an array of eslint messages (object). The function must return the output as a string. You can use official eslint formatters.
module.exports = {
entry: "...",
module: {
// ...
}
eslint: {
// several examples !
// default value
formatter: require("eslint/lib/formatters/stylish"),
// community formatter
formatter: require("eslint-friendly-formatter"),
// custom formatter
formatter: function(results) {
// `results` format is available here
// http://eslint.org/docs/developer-guide/nodejs-api.html#executeonfiles()
// you should return a string
// DO NOT USE console.*() directly !
return "OUTPUT"
}
}
}
By default the loader will auto adjust error reporting depending
on eslint errors/warnings counts.
You can still force this behavior by using emitError
or emitWarning
options:
Loader will always return errors if this option is set to true
.
module.exports = {
entry: "...",
module: {
// ...
},
eslint: {
emitError: true
}
}
Loader will always return warnings if option is set to true
.
Loader will process and report errors only and ignore warnings if this option is set to true
module.exports = {
entry: "...",
module: {
// ...
},
eslint: {
quiet: true
}
}
Loader will cause the module build to fail if there are any eslint warnings.
module.exports = {
entry: "...",
module: {
// ...
},
eslint: {
failOnWarning: true
}
}
Loader will cause the module build to fail if there are any eslint errors.
module.exports = {
entry: "...",
module: {
// ...
},
eslint: {
failOnError: true
}
}
NoErrorsPlugin
prevents Webpack from outputting anything into a bundle. So even ESLint warnings
will fail the build. No matter what error settings are used for eslint-loader
.
So if you want to see ESLint warnings in console during development using WebpackDevServer
remove NoErrorsPlugin
from webpack config.