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5 changes: 5 additions & 0 deletions .changeset/sad-points-strive.md
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---
'eslint-plugin-svelte': minor
---

Added `no-add-event-listener` rule to disallow usages of `addEventListener`
1 change: 1 addition & 0 deletions README.md
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Expand Up @@ -294,6 +294,7 @@ These rules relate to better ways of doing things to help you avoid problems:
|:--------|:------------|:---|
| [svelte/block-lang](https://sveltejs.github.io/eslint-plugin-svelte/rules/block-lang/) | disallows the use of languages other than those specified in the configuration for the lang attribute of `<script>` and `<style>` blocks. | :bulb: |
| [svelte/button-has-type](https://sveltejs.github.io/eslint-plugin-svelte/rules/button-has-type/) | disallow usage of button without an explicit type attribute | |
| [svelte/no-add-event-listener](https://sveltejs.github.io/eslint-plugin-svelte/rules/no-add-event-listener/) | Warns against the use of `addEventListener` | :bulb: |
| [svelte/no-at-debug-tags](https://sveltejs.github.io/eslint-plugin-svelte/rules/no-at-debug-tags/) | disallow the use of `{@debug}` | :star::bulb: |
| [svelte/no-ignored-unsubscribe](https://sveltejs.github.io/eslint-plugin-svelte/rules/no-ignored-unsubscribe/) | disallow ignoring the unsubscribe method returned by the `subscribe()` on Svelte stores. | |
| [svelte/no-immutable-reactive-statements](https://sveltejs.github.io/eslint-plugin-svelte/rules/no-immutable-reactive-statements/) | disallow reactive statements that don't reference reactive values. | :star: |
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1 change: 1 addition & 0 deletions docs/rules.md
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Expand Up @@ -51,6 +51,7 @@ These rules relate to better ways of doing things to help you avoid problems:
| :--------------------------------------------------------------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------- | :------------- |
| [svelte/block-lang](./rules/block-lang.md) | disallows the use of languages other than those specified in the configuration for the lang attribute of `<script>` and `<style>` blocks. | :bulb: |
| [svelte/button-has-type](./rules/button-has-type.md) | disallow usage of button without an explicit type attribute | |
| [svelte/no-add-event-listener](./rules/no-add-event-listener.md) | Warns against the use of `addEventListener` | :bulb: |
| [svelte/no-at-debug-tags](./rules/no-at-debug-tags.md) | disallow the use of `{@debug}` | :star::bulb: |
| [svelte/no-ignored-unsubscribe](./rules/no-ignored-unsubscribe.md) | disallow ignoring the unsubscribe method returned by the `subscribe()` on Svelte stores. | |
| [svelte/no-immutable-reactive-statements](./rules/no-immutable-reactive-statements.md) | disallow reactive statements that don't reference reactive values. | :star: |
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50 changes: 50 additions & 0 deletions docs/rules/no-add-event-listener.md
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---
pageClass: 'rule-details'
sidebarDepth: 0
title: 'svelte/no-add-event-listener'
description: 'Warns against the use of `addEventListener`'
---

# svelte/no-add-event-listener

> Warns against the use of `addEventListener`

- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> **_This rule has not been released yet._** </badge>
- :bulb: Some problems reported by this rule are manually fixable by editor [suggestions](https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions).

## :book: Rule Details

Svelte relies on event delegation for performance and predictable handler order. Calling `addEventListener` inside a component skips this mechanism. This rule reports any call to `addEventListener` suggests converting to the `on()` helper from `svelte/events`.

<!--eslint-skip-->

```svelte
<!-- ✓ GOOD -->
<script>
/* eslint svelte/no-add-event-listener: "error" */
on(window, 'resize', handler);
</script>
```

<!--eslint-skip-->

```svelte
<!-- ✗ BAD -->
<script>
/* eslint svelte/no-add-event-listener: "error" */
window.addEventListener('resize', handler);
</script>
```

## :books: Further reading

- [svelte - event delegation]
- [svelte/events `on` documentation]

[svelte - event delegation]: https://svelte.dev/docs/svelte/basic-markup#Events-Event-delegation
[svelte/events `on` documentation]: https://svelte.dev/docs/svelte/svelte-events#on

## :mag: Implementation

- [Rule source](https://github.com/sveltejs/eslint-plugin-svelte/blob/main/packages/eslint-plugin-svelte/src/rules/no-add-event-listener.ts)
- [Test source](https://github.com/sveltejs/eslint-plugin-svelte/blob/main/packages/eslint-plugin-svelte/tests/src/rules/no-add-event-listener.ts)
5 changes: 5 additions & 0 deletions packages/eslint-plugin-svelte/src/rule-types.ts
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Expand Up @@ -99,6 +99,11 @@ export interface RuleOptions {
* @see https://sveltejs.github.io/eslint-plugin-svelte/rules/mustache-spacing/
*/
'svelte/mustache-spacing'?: Linter.RuleEntry<SvelteMustacheSpacing>
/**
* Warns against the use of `addEventListener`
* @see https://sveltejs.github.io/eslint-plugin-svelte/rules/no-add-event-listener/
*/
'svelte/no-add-event-listener'?: Linter.RuleEntry<[]>
/**
* disallow the use of `{@debug}`
* @see https://sveltejs.github.io/eslint-plugin-svelte/rules/no-at-debug-tags/
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69 changes: 69 additions & 0 deletions packages/eslint-plugin-svelte/src/rules/no-add-event-listener.ts
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import type { TSESTree } from '@typescript-eslint/types';

import { createRule } from '../utils/index.js';
import type { SuggestionReportDescriptor } from '../types.js';

export default createRule('no-add-event-listener', {
meta: {
docs: {
description: 'Warns against the use of `addEventListener`',
category: 'Best Practices',
recommended: false
},
hasSuggestions: true,
schema: [],
messages: {
unexpected:
'Do not use `addEventListener`. Use the `on` function from `svelte/events` instead.'
},
type: 'suggestion',
conditions: [
{
svelteVersions: ['5']
}
]
},
create(context) {
return {
CallExpression(node: TSESTree.CallExpression) {
const { callee, arguments: args } = node;
let target: string | null = null;

if (
callee.type === 'MemberExpression' &&
callee.property.type === 'Identifier' &&
callee.property.name === 'addEventListener'
) {
target = context.sourceCode.getText(callee.object);
} else if (callee.type === 'Identifier' && callee.name === 'addEventListener') {
target = 'window';
}

if (target === null) {
return;
}

const openParen = context.sourceCode.getTokenAfter(callee);
const suggest: SuggestionReportDescriptor[] = [];

if (openParen !== null) {
suggest.push({
desc: 'Use `on` from `svelte/events` instead',
fix(fixer) {
return [
fixer.replaceText(callee, 'on'),
fixer.insertTextAfter(openParen, `${target}, `)
];
}
});
}

context.report({
node,
messageId: 'unexpected',
suggest
});
}
};
}
});
2 changes: 2 additions & 0 deletions packages/eslint-plugin-svelte/src/utils/rules.ts
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Expand Up @@ -19,6 +19,7 @@ import indent from '../rules/indent.js';
import infiniteReactiveLoop from '../rules/infinite-reactive-loop.js';
import maxAttributesPerLine from '../rules/max-attributes-per-line.js';
import mustacheSpacing from '../rules/mustache-spacing.js';
import noAddEventListener from '../rules/no-add-event-listener.js';
import noAtDebugTags from '../rules/no-at-debug-tags.js';
import noAtHtmlTags from '../rules/no-at-html-tags.js';
import noDomManipulating from '../rules/no-dom-manipulating.js';
Expand Down Expand Up @@ -94,6 +95,7 @@ export const rules = [
infiniteReactiveLoop,
maxAttributesPerLine,
mustacheSpacing,
noAddEventListener,
noAtDebugTags,
noAtHtmlTags,
noDomManipulating,
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{
"svelte": ">=5.0.0-0"
}
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