no-duplicate-imports.md

Disallow duplicate imports (no-duplicate-imports)

Using a single import statement per module will make the code clearer because you can see everything being imported from that module on one line.

In the following example the module import on line 1 is repeated on line 3. These can be combined to make the list of imports more succinct.

import { merge } from 'module';
import something from 'another-module';
import { find } from 'module';

Rule Details

An import that can be merged with another is a duplicate of that other.

This rule requires that all imports from a single module that can be merged exists in a single import statement.

Example of incorrect code for this rule:

/*eslint no-duplicate-imports: "error"*/

import { merge } from 'module';
import something from 'another-module';
import { find } from 'module';

Example of correct code for this rule:

/*eslint no-duplicate-imports: "error"*/

import { merge, find } from 'module';
import something from 'another-module';

Example of correct code for this rule:

// not mergable, as they would require new nodes to be created.
import { merge } from 'module';
import * as something from 'module';

Options

This rule takes one optional argument, an object with a single key, includeExports which is a boolean. It defaults to false.

If re-exporting from an imported module, you should add the imports to the import-statement, and export that directly, not use export ... from.

Example of incorrect code for this rule with the { "includeExports": true } option:

/*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/

import { merge } from 'module';

export { find } from 'module';

Example of correct code for this rule with the { "includeExports": true } option:

/*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/

import { merge, find } from 'module';

export { find };

There is a special case even the export is duplicate we ignore it, because it can't be merged with another import/export from the same source, it's when we have export with type export *.

Example of correct code for this rule with the { "includeExports": true } option:

import { merge, find } from 'module';

export * from 'module';