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no-single-line-comment

Disallow // comments and require block comments instead.

Targeted pattern scope​

This rule targets all line comments (// ...) in source files.

What this rule reports​

This rule reports line comments unless they are directive comments that are explicitly allowed by configuration.

Why this rule exists​

Single-line comments are easy to accumulate as stale notes and are harder to format consistently in long explanations. This rule reports line comments and encourages block comments.

❌ Incorrect​

// update this later
const value = 1;

✅ Correct​

/* update this later */
const value = 1;

Behavior and migration notes​

This rule reports only and does not provide an autofix.

Options​

type Options = [
 {
  allowDirectiveComments?: boolean;
 }?,
];

Default configuration​

Default:

[{ allowDirectiveComments: true }];

When allowDirectiveComments is true, comments such as // eslint-disable-next-line ... and // @ts-expect-error are allowed.

Additional examples​

// eslint-disable-next-line no-console
console.log("x");
// ✅ allowed by default (`allowDirectiveComments: true`)

// TODO: refactor this
const value = 1;
// ❌ reported

/* TODO: refactor this */
const nextValue = 2;
// ✅ valid

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/no-single-line-comment": "error",
  },
 },
];

When not to use it​

Disable this rule if your team standardizes on // comments for short inline notes.

Package documentation​

Rule catalog ID: R042

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.