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consistent-empty-lines

Enforce configured empty-line consistency between selected nodes.

Targeted pattern scope​

This rule operates on the full file text and checks for runs of empty lines.

It allows:

  • zero empty lines, or
  • exactly one empty line between non-empty lines.

It reports when it finds two or more consecutive empty lines.

What this rule reports​

This rule reports files containing consecutive blank-line runs longer than one line.

An autofix is provided and collapses each run to a single blank line.

Why this rule exists​

Extra vertical whitespace often accumulates during edits and merge conflict resolution. Enforcing a single-blank-line maximum keeps files visually dense and reduces noisy formatting diffs.

❌ Incorrect​

const first = 1;

const second = 2;

✅ Correct​

const first = 1;

const second = 2;

Behavior and migration notes​

This rule is fully autofixable (fixable: "whitespace").

Recommended rollout:

  1. Run once with --fix-dry-run to estimate churn.
  2. Apply autofix in a dedicated formatting PR.
  3. Enable as error to keep the baseline clean.

Options​

This rule has no options.

Additional examples​

function run(): void {
 stepOne();

 stepTwo();
}

ESLint flat config example​

import etcMisc from "eslint-plugin-etc-misc";

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/consistent-empty-lines": "error",
  },
 },
];

When not to use it​

Disable this rule if your style guide intentionally allows multiple blank lines for sectioning or if another formatter already controls vertical spacing exactly as desired.

Package documentation​

Rule catalog ID: R004

Further reading​

Adoption resources​

  • Start at warning level in CI, then move to error after cleanup.
  • Use focused codemods/autofix batches per package or directory.