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import/no-duplicates Style

What it does

Reports if a resolved path is imported more than once in the same module. This helps avoid unnecessary duplicate imports and keeps the code clean.

Why is this bad?

Importing the same module multiple times can lead to redundancy and unnecessary complexity. It also affects maintainability, as it might confuse developers and result in inconsistent usage of imports across the code.

Examples

Examples of incorrect code for this rule:

import { foo } from "./module";
import { bar } from "./module";

import a from "./module";
import { b } from "./module";

Examples of correct code for this rule:

import { foo, bar } from "./module";

import * as a from "foo"; // separate statements for namespace imports
import { b } from "foo";

import { c } from "foo"; // separate type imports, unless
import type { d } from "foo"; // `prefer-inline` is true

Configuration

This rule accepts a configuration object with the following properties:

considerQueryString

type: boolean

default: false

When set to true, the rule will consider the query string part of the import path when determining if imports are duplicates. This is useful when using loaders like webpack that use query strings to configure how a module should be loaded.

Examples of correct code with this option set to true:

import x from "./bar?optionX";
import y from "./bar?optionY";

preferInline

type: boolean

default: false

When set to true, prefer inline type imports instead of separate type import statements for TypeScript code.

Examples of correct code with this option set to true:

import { Foo, type Bar } from "./module";

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "plugins": ["import"],
  "rules": {
    "import/no-duplicates": "error"
  }
}

CLI

oxlint --deny import/no-duplicates --import-plugin

References

• Rule Source