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feat: add allow options to no-empty-definitions #455

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283dfc4
feat: add allow options to no-empty-definitions
TKDev7 Jul 2, 2025
491e4c4
context.options[0] is always present
TKDev7 Jul 2, 2025
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36 changes: 29 additions & 7 deletions docs/rules/no-empty-definitions.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ Definitions with an empty URL or only an empty fragment (`#`), as well as footno
>
> Footnotes are only supported when using `language` mode [`markdown/gfm`](/README.md#languages).

This rule warns when it finds definitions where the URL is either not specified or contains only an empty fragment (`#`). It also warns for empty footnote definitions by default.
This rule warns when it finds definitions where the URL is either not specified or contains only an empty fragment (`#`). It also warns for empty footnote definitions by default. Please note that this rule doesn't report definition-style comments (e.g., `[//]: # (This is a comment)`) by default.

Examples of **incorrect** code for this rule:

Expand All @@ -43,22 +43,44 @@ Examples of **correct** code for this rule:

[earth]: https://example.com/earth/
[moon]: #section
[//]: <> (This is a comment 1)
[//]: # (This is a comment 2)
[^note]: This is a footnote.
```

## Options

The following options are available on this rule:

* `checkFootnoteDefinitions: boolean` - When set to `false`, the rule will not report empty footnote definitions. (default: `true`).
- `allowDefinitions: Array<string>` - When specified, empty definitions are allowed if they match one of the identifiers in this array. This is useful for ignoring definitions that are intentionally empty. (default: `["//"]`)

Examples of **correct** code for this rule with `checkFootnoteDefinitions: false`:
Examples of **correct** code when configured as `"no-empty-definitions": ["error", { allowDefinitions: ["moon"] }]`:

```markdown
<!-- eslint markdown/no-empty-definitions: ["error", { checkFootnoteDefinitions: false }] -->
```markdown
<!-- eslint markdown/no-empty-definitions: ["error", { allowDefinitions: ["moon"] }] -->

[^note]:
```
[moon]: <>
```

- `allowFootnoteDefinitions: Array<string>` - When specified, empty footnote definitions are allowed if they match one of the identifiers in this array. This is useful for ignoring footnote definitions that are intentionally empty. (default: `[]`)

Examples of **correct** code when configured as `"no-empty-definitions": ["error", { allowFootnoteDefinitions: ["note"] }]`:

```markdown
<!-- eslint markdown/no-empty-definitions: ["error", { allowFootnoteDefinitions: ["note"] }] -->

[^note]:
```

- `checkFootnoteDefinitions: boolean` - When set to `false`, the rule will not report empty footnote definitions. (default: `true`)

Examples of **correct** code when configured as `"no-empty-definitions": ["error", { checkFootnoteDefinitions: false }]`:

```markdown
<!-- eslint markdown/no-empty-definitions: ["error", { checkFootnoteDefinitions: false }] -->

[^note]:
```

## When Not to Use It

Expand Down
34 changes: 31 additions & 3 deletions src/rules/no-empty-definitions.js
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Expand Up @@ -10,7 +10,7 @@
/**
* @import { MarkdownRuleDefinition } from "../types.js";
* @typedef {"emptyDefinition" | "emptyFootnoteDefinition"} NoEmptyDefinitionsMessageIds
* @typedef {[{ checkFootnoteDefinitions?: boolean }]} NoEmptyDefinitionsOptions
* @typedef {[{ allowDefinitions?: string[], allowFootnoteDefinitions?: string[], checkFootnoteDefinitions?: boolean }]} NoEmptyDefinitionsOptions
* @typedef {MarkdownRuleDefinition<{ RuleOptions: NoEmptyDefinitionsOptions, MessageIds: NoEmptyDefinitionsMessageIds }>} NoEmptyDefinitionsRuleDefinition
*/

Expand Down Expand Up @@ -56,6 +56,20 @@ export default {
{
type: "object",
properties: {
allowDefinitions: {
type: "array",
items: {
type: "string",
},
uniqueItems: true,
},
allowFootnoteDefinitions: {
type: "array",
items: {
type: "string",
},
uniqueItems: true,
},
checkFootnoteDefinitions: {
type: "boolean",
},
Expand All @@ -64,15 +78,28 @@ export default {
},
],

defaultOptions: [{ checkFootnoteDefinitions: true }],
defaultOptions: [
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Copilot AI Jul 2, 2025

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Because ESLint does not deep-merge defaultOptions with a user-supplied options object, users who specify only one property will lose the defaults for the others. Consider destructuring context.options[0] with in-function defaults (e.g., const { allowDefinitions = ["//"], allowFootnoteDefinitions = [], checkFootnoteDefinitions = true } = context.options[0] || {};) to ensure all defaults apply even when partial options are provided.

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{
allowDefinitions: ["//"],
allowFootnoteDefinitions: [],
checkFootnoteDefinitions: true,
},
],
},

create(context) {
const allowDefinitions = new Set(context.options[0]?.allowDefinitions);
const allowFootnoteDefinitions = new Set(
context.options[0]?.allowFootnoteDefinitions,
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Using optional chaining here assumes allowDefinitions is always provided via defaultOptions. If a user passes an empty object, this will be undefined. You may want to explicitly default to an empty array to avoid unexpected behavior: new Set(context.options[0]?.allowDefinitions || []).

Suggested change
const allowDefinitions = new Set(context.options[0]?.allowDefinitions);
const allowFootnoteDefinitions = new Set(
context.options[0]?.allowFootnoteDefinitions,
const allowDefinitions = new Set(context.options[0]?.allowDefinitions || []);
const allowFootnoteDefinitions = new Set(
context.options[0]?.allowFootnoteDefinitions || [],

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);
const [{ checkFootnoteDefinitions }] = context.options;

return {
definition(node) {
if (!node.url || node.url === "#") {
if (
(!node.url || node.url === "#") &&
!allowDefinitions.has(node.identifier)
) {
context.report({
loc: node.position,
messageId: "emptyDefinition",
Expand All @@ -83,6 +110,7 @@ export default {
footnoteDefinition(node) {
if (
checkFootnoteDefinitions &&
!allowFootnoteDefinitions.has(node.identifier) &&
(node.children.length === 0 ||
node.children.every(
child =>
Expand Down
71 changes: 71 additions & 0 deletions tests/rules/no-empty-definitions.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@ ruleTester.run("no-empty-definitions", rule, {
"[foo]: #bar",
"[foo]: http://bar.com",
"[foo]: <https://bar.com>",
"[//]: # (This is a comment 1)",
"[//]: <> (This is a comment 2)",
"[^note]: This is a footnote.",
"[^note]: ![]()",
"[^note]: [text](url)",
Expand All @@ -47,10 +49,31 @@ ruleTester.run("no-empty-definitions", rule, {
[^foo]: <!-- comm
ent --> content <!-- comment -->
`,
{
code: "[foo]: #",
options: [{ allowDefinitions: ["foo"] }],
},
{
code: "[bar]: <>",
options: [{ allowDefinitions: ["bar"] }],
},
{
code: "[foo]: #\n[bar]: <>",
options: [{ allowDefinitions: ["foo", "bar"] }],
},
{
code: "[^note]:",
options: [{ checkFootnoteDefinitions: false }],
},
{
code: "[^note]:",
options: [
{
checkFootnoteDefinitions: true,
allowFootnoteDefinitions: ["note"],
},
],
},
],
invalid: [
{
Expand Down Expand Up @@ -226,5 +249,53 @@ ruleTester.run("no-empty-definitions", rule, {
},
],
},
{
code: "[//]: #\n[foo]: #",
errors: [
{
messageId: "emptyDefinition",
line: 2,
column: 1,
endLine: 2,
endColumn: 9,
},
],
},
{
code: "[foo]: #",
options: [
{
allowDefinitions: ["bar"],
allowFootnoteDefinitions: ["foo"],
},
],
errors: [
{
messageId: "emptyDefinition",
line: 1,
column: 1,
endLine: 1,
endColumn: 9,
},
],
},
{
code: "[^foo]:",
options: [
{
allowDefinitions: ["foo"],
allowFootnoteDefinitions: ["bar"],
},
],
errors: [
{
messageId: "emptyFootnoteDefinition",
line: 1,
column: 1,
endLine: 1,
endColumn: 8,
},
],
},
],
});