@inca/eslint-no-blank-lines-in-blocks

ESLint plugin rule that disallows blank lines inside code blocks.

Why this rule

Blank lines inside small code blocks are often a signal that logic is doing too much in one place. Among other things, this rule helps coding agents write more focused blocks and add meaningful structure instead of whitespace-based grouping.

Install

npm install --save-dev @inca/eslint-no-blank-lines-in-blocks eslint

Usage (Flat Config)

import noBlankLinesInBlocks from '@inca/eslint-no-blank-lines-in-blocks';

export default [
    noBlankLinesInBlocks.configs.recommended,
];

Or configure manually:

import noBlankLinesInBlocks from '@inca/eslint-no-blank-lines-in-blocks';

export default [
    {
        plugins: {
            '@inca/no-blank-lines-in-blocks': noBlankLinesInBlocks,
        },
        rules: {
            '@inca/no-blank-lines-in-blocks/no-blank-lines-in-blocks': 'error',
        },
    },
];

Optionally allow a single blank line before a comment block:

import noBlankLinesInBlocks from '@inca/eslint-no-blank-lines-in-blocks';

export default [
    {
        plugins: {
            '@inca/no-blank-lines-in-blocks': noBlankLinesInBlocks,
        },
        rules: {
            '@inca/no-blank-lines-in-blocks/no-blank-lines-in-blocks': [
                'error',
                { allowSingleBlankLineBeforeComment: true },
            ],
        },
    },
];

You can also disable autofix while still reporting violations:

import noBlankLinesInBlocks from '@inca/eslint-no-blank-lines-in-blocks';

export default [
    {
        plugins: {
            '@inca/no-blank-lines-in-blocks': noBlankLinesInBlocks,
        },
        rules: {
            '@inca/no-blank-lines-in-blocks/no-blank-lines-in-blocks': [
                'error',
                { enableFix: false },
            ],
        },
    },
];

Examples

Method

Invalid:

class Service {
    run(): void {
        const value = 1;

        console.log(value);
    }
}

Valid:

class Service {
    run(): void {
        const value = 1;
        console.log(value);
    }
}

Function

Invalid:

function process(input: string): string {
    const normalized = input.trim();

    return normalized.toUpperCase();
}

Valid:

function process(input: string): string {
    const normalized = input.trim();
    return normalized.toUpperCase();
}

If block

Invalid:

if (isReady) {
    initialize();

    run();
}

Valid:

if (isReady) {
    initialize();
    run();
}

For loop

Invalid:

for (const item of items) {
    const normalized = normalize(item);

    output.push(normalized);
}

Valid:

for (const item of items) {
    const normalized = normalize(item);
    output.push(normalized);
}