Configuration

Linting with Flint must be configured by at least one flint.config.* configuration file, in the root of a repository to be linted. That file may be any extension recognized by your version of Node.js.

Flint configs must default-export the result of calling the defineConfig function imported from the flint package. flint also exports a globs object for common file globs, as well as objects for each of the core plugins.

defineConfig

Defines a new configuration for linting. It takes in an object with one required property, use:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: ts.files.all,
      rules: ts.presets.logical,
    },
  ],
});

ignore

A list of glob patterns to ignore from linting. This can be a string, any level deep array of strings, or an object containing exclude and include.

ignore by default includes all patterns defined in a .gitignore file, if it exists.

This ignore directive ignores all files under src/legacy/:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  ignore: ["src/legacy/**/*"],
  use: [
    {
      files: ts.files.all,
      rules: ts.presets.logical,
    },
  ],
});

use

The only required object property to pass to defineConfig is use, an array of definitions containing two properties:

• files: glob pattern(s) describing which file(s) to lint
• rules: any number of rules to enable for those files

files

Any number of glob pattern(s) describing file(s) to lint. This can be a string, any level deep array of strings, or an object containing exclude and include.

For example, this files selector matches all TypeScript test files by extension and in a directory:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: ["src/**/*.test.*.ts", "test/**/*.ts"],
      rules: ts.presets.logical,
    },
  ],
});

See the Node.js file system glob documentation for details on glob patterns.

exclude and include

In addition to plain strings, files selectors can also be objects with two properties:

• exclude: glob pattern(s) to not include in the files group
• include: glob pattern(s) to include in the files group

For example, this files selector matches all TypeScript source files that don’t have a *.test.* extension:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: {
        exclude: "**/*.test.*",
        include: ts.files.all,
      },
      rules: ts.presets.logical,
    },
  ],
});

rules

Any number of rule(s) to enable on the corresponding files. These may be arrays of rules, such as from presets exported by plugins, and/or calls to plugin rules themselves.

For example, this rules entry enables all the recommended logical and stylistic TypeScript rules:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: ts.files.all,
      rules: [ts.presets.logical, ts.presets.stylistic],
    },
  ],
});

Configuring Rules

Rules can be configured or disabled by calling to the rules method of their plugin. That method takes in an object where the keys are rule names and values are what to do with the rule:

• true: enable it (if it wasn’t already)
• false: disable it (if it was previously enabled)
• Object containing options: enable it with those options

For example, this rules entry disables one rule and reconfigures another:

flint.config.ts

import { defineConfig, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: ts.files.all,
      rules: [
        ts.presets.logical,
        ts.presets.stylistic,
        ts.rules({
          debuggerStatements: false,
          namespaceDeclarations: {
            allowDeclarations: true,
          },
        }),
      ],
    },
  ],
});

globs

A helper object containing file selectors with dynamic computed values. Currently it contains only one selector, all.

all

Includes all files previously selected by the configuration.

For example, this config enables the spelling plugin on all files that are being linted, which includes multiple languages:

flint.config.ts

import { spelling } from "@flint.fyi/spelling";
import { defineConfig, globs, md, ts } from "flint";

export default defineConfig({
  use: [
    {
      files: md.files.all,
      rules: md.presets.logical,
    },
    {
      files: ts.files.all,
      rules: [ts.presets.logical, ts.presets.stylistic],
    },
    {
      files: globs.all,
      rules: spelling.presets.logical,
    },
  ],
});

Inline Directives

You can also disable specific rules inline in your code using comment directives. This is useful when you need to suppress a rule for a specific line, block, or file.

Workspaces

Danger

Flint configuration workspaces are not yet implemented. See flint-fyi/flint#64 🚀 Feature: Config file workspaces support for details.