gulp-eslint-new

A gulp plugin to lint code with ESLint 8

Usage no npm install needed!

<script type="module">
  import gulpEslintNew from 'https://cdn.skypack.dev/gulp-eslint-new';
</script>

README

gulp-eslint-new ยท npm version

A gulp plugin to lint code with ESLint 8

Installation

Use npm:

npm i -D gulp-eslint-new

Migrating

If you are migrating from gulp-eslint, you probably won't need to change any settings in your gulp task. gulp-eslint-new can handle most of the options used with gulp-eslint, although some of them are now deprecated in favor of a new name or format.

Anyway, since gulp-eslint-new uses ESLint 8 while gulp-eslint sticks to ESLint 6, you may need to make some changes to your project to address incompatibilities between the versions of ESLint. You can find more information at the links below.

Usage

const { src } = require('gulp');
const gulpESLintNew = require('gulp-eslint-new');

// Define the default gulp task.
exports.default =
    () => src(['scripts/*.js'])
    // gulpESLintNew() attaches the lint output to the "eslint" property of the
    // file object so it can be used by other modules.
    .pipe(gulpESLintNew())
    // gulpESLintNew.format() outputs the lint results to the console.
    // Alternatively use gulpESLintNew.formatEach() (see docs).
    .pipe(gulpESLintNew.format())
    // To have the process exit with an error code (1) on lint error, return the
    // stream and pipe to failAfterError last.
    .pipe(gulpESLintNew.failAfterError());

Or use the plugin API to do things like:

gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew({
        overrideConfig: {
            plugins: ['json'],
            extends: ['plugin:json/recommended'],
            rules: {
                'my-custom-rule': 1,
                'strict': 2
            },
            globals: {
                jQuery: 'readonly',
                $: 'readonly'
            },
            env: {
                'browser': true
            }
        },
        warnIgnored: true
    }))
    .pipe(gulpESLintNew.formatEach('compact', process.stderr));

For additional examples, look through the example directory.

API

gulpESLintNew()

No explicit configuration. A .eslintrc file may be resolved relative to each linted file.

gulpESLintNew(options)

Param type: Object

Supported options include all linting options and autofix options of the ESLint constructor. Please, refer to the ESLint documentation for information about the usage of those options. Check also the notes about the Autofix Function. Additionally, gulp-eslint-new supports the options listed below.

Additional Options

options.cwd

Type: string

The working directory. This must be an absolute path. Default is the current working directory.

The working directory is where ESLint will look for a .eslintignore file by default. It is also the base directory for any relative paths specified in the options (e.g. options.overrideConfigFile, options.resolvePluginsRelativeTo, options.rulePaths, options.overrideConfig.extends, etc.). The location of the files to be linted is not related to the working directory.

options.ignore

Type: boolean

When false, ESLint will not respect .eslintignore files or ignore patterns in your configurations.

options.ignorePath

Type: string

The path to a file ESLint uses instead of .eslintignore in the current working directory.

options.quiet

Type: boolean

When true, this option will filter warning messages from ESLint results. This mimics the ESLint CLI --quiet option.

Type: (message: string, index: number, list: Object[]) => unknown

When a function is provided, it will be used to filter ESLint result messages, removing any messages that do not return a true (or truthy) value.

options.warnIgnored

Type: boolean

When true, add a result warning when ESLint ignores a file. This can be used to find files that are needlessly being loaded by gulp.src. For example, since ESLint automatically ignores file paths inside a node_modules directory but gulp.src does not, a gulp task may take seconds longer just reading files from node_modules.

Legacy Options

The following legacy options are provided for backward compatibility with gulp-eslint. When gulpESLintNew is passed any of these options, it will map them automatically as shown in the table to match the new ESLint conventions.

| Legacy option | Migrated to | Notes | |-------------------|---------------------------------|-| | configFile | overrideConfigFile | New option name. | | envs | overrideConfig.env | New option name and format. overrideConfig.env should be an object as explained in the documentation. | | extends | overrideConfig.extends | | | globals | overrideConfig.globals | The new option format requires overrideConfig.globals to be an object as explained in the documentation. | | ignorePattern | overrideConfig.ignorePatterns | New option name. | | parser | overrideConfig.parser | | | parserOptions | overrideConfig.parserOptions | | | plugins | overrideConfig.plugins | plugins as an array of strings is migrated to overrideConfig.plugins. In contrast, plugins as an object that maps strings to plugin implementations has different semantics and is not migrated. | | rules | overrideConfig.rules | | | warnFileIgnored | warnIgnored | New option name. |

Autofix Function

When the fix option is specified, fixes are applied to the gulp stream. The fixed content can be saved to file using gulpESLintNew.fix() (See example/fix.js). Rules that are fixable can be found in ESLint's rules list. When fixes are applied, a fixed property is set to true on the fixed file's ESLint result.

gulpESLintNew(overrideConfigFile)

Param type: string

Shorthand for defining options.overrideConfigFile.

gulpESLintNew.result(action)

Param type: (result: Object) => void

Call a function for each ESLint file result. No returned value is expected. If an error is thrown, it will be wrapped in a gulp PluginError and emitted from the stream.

gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew())
    .pipe(gulpESLintNew.result(result => {
        // Called for each ESLint result.
        console.log(`ESLint result: ${result.filePath}`);
        console.log(`# Messages: ${result.messages.length}`);
        console.log(`# Warnings: ${result.warningCount} (${
            result.fixableWarningCount} fixable)`);
        console.log(`# Errors: ${result.errorCount} (${
            result.fixableErrorCount} fixable, ${
            result.fatalErrorCount} fatal)`);
    }));

Param Type: (result: Object, callback: Function) => void

Call an asynchronous, Node-style callback-based function for each ESLint file result. The callback must be called for the stream to finish. If an error is passed to the callback, it will be wrapped in a gulp PluginError and emitted from the stream.

Param Type: (result: Object) => Promise<void>

Call an asynchronous, promise-based function for each ESLint file result. If the promise is rejected, the rejection reason will be wrapped in a gulp PluginError and emitted from the stream.

gulpESLintNew.results(action)

Param type: (results: Object[]) => void

Call a function once for all ESLint file results before a stream finishes. No returned value is expected. If an error is thrown, it will be wrapped in a gulp PluginError and emitted from the stream.

The results list has additional properties that indicate the number of messages of a certain kind.

errorCount number of errors
warningCount number of warnings
fixableErrorCount number of fixable errors
fixableWarningCount number of fixable warnings
fatalErrorCount number of fatal errors 
gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew())
    .pipe(gulpESLintNew.results(results => {
        // Called once for all ESLint results.
        console.log(`Total Results: ${results.length}`);
        console.log(`Total Warnings: ${results.warningCount} (${
            results.fixableWarningCount} fixable)`);
        console.log(`Total Errors: ${results.errorCount} (${
            results.fixableErrorCount} fixable, ${
            results.fatalErrorCount} fatal)`);
    }));

Param type: (results: Object[], callback: Function) => void

Call an asynchronous, Node-style callback-based function once for all ESLint file results before a stream finishes. The callback must be called for the stream to finish. If an error is passed to the callback, it will be wrapped in a gulp PluginError and emitted from the stream.

Param type: (results: Object[]) => Promise<void>

Call an asynchronous, promise-based function once for all ESLint file results before a stream finishes. If the promise is rejected, the rejection reason will be wrapped in a gulp PluginError and emitted from the stream.

gulpESLintNew.failOnError()

Stop a task/stream if an ESLint error has been reported for any file.

// Cause the stream to stop (fail) without processing more files.
gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew())
    .pipe(gulpESLintNew.failOnError());

gulpESLintNew.failAfterError()

Stop a task/stream if an ESLint error has been reported for any file, but wait for all of them to be processed first.

// Cause the stream to stop (fail) when the stream ends if any ESLint error(s)
// occurred.
gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew())
    .pipe(gulpESLintNew.failAfterError());

gulpESLintNew.format(formatter, writer)

Format all linted files once. This should be used in the stream after piping through gulpESLintNew; otherwise, this will find no ESLint results to format.

formatter param type: string | Object | Function | undefined

The formatter argument determines the ESLint formatter used to format linting results. If a string is provided, a formatter module by that name or path will be resolved. The resolved formatter will be either one of the built-in ESLint formatters, or a formatter exported by a module with the specified path (located relative to the ESLint working directory), or a formatter exported by a package installed as a dependency (the prefix "eslint-formatter-" in the package name can be omitted). Instead of providing a string, it is also possible to specify a formatter object as resolved by the ESLint method loadFormatter, or a formatter function directly. If undefined is specified, the ESLint "stylish" formatter will be used.

// Use the default "stylish" ESLint formatter.
gulpESLintNew.format()

// Use the "checkstyle" ESLint formatter.
gulpESLintNew.format('checkstyle')

// Use "eslint-formatter-pretty" as a formatter (must be installed with `npm`).
// See https://github.com/sindresorhus/eslint-formatter-pretty.
gulpESLintNew.format('pretty')

writer param type: NodeJS.WritableStream | Function | undefined

The writer argument may be a writable stream, Function, or undefined. As a writable stream, the formatter output will be written to the stream. If undefined, the formatter output will be written to gulp's log. A Function will be called with the formatter output as the only parameter.

// write to gulp's log (default)
gulpESLintNew.format()

// write messages to stdout
gulpESLintNew.format('junit', process.stdout)

gulpESLintNew.formatEach(formatter, writer)

Format each linted file individually. This should be used in the stream after piping through gulpESLintNew; otherwise, this will find no ESLint results to format.

The arguments for gulpESLintNew.formatEach are the same as the arguments for gulpESLintNew.format.

gulpESLintNew.fix()

Overwrite files with the fixed content provided by ESLint. This should be used in conjunction with the option fix in gulpESLintNew(options). Files without a fix and files that were not processed by ESLint will be left untouched.

gulp.src(['**/*.js', '!node_modules/**'])
    .pipe(gulpESLintNew({ fix: true }))
    .pipe(gulpESLintNew.fix());

Configuration

ESLint may be configured explicity by using any of the supported configuration options. Unless the useEslintrc option is set to false, ESLint will attempt to resolve a file by the name of .eslintrc within the same directory as the file to be linted. If not found there, parent directories will be searched until .eslintrc is found or the directory root is reached.

Custom Extensions

ESLint results are attached as an eslint property to the Vinyl files that pass through a gulp stream pipeline. This is available to streams that follow the initial gulp-eslint-new stream. The functions gulpESLintNew.result and gulpESLintNew.results are made available to support extensions and custom handling of ESLint results.