feat: add new rule no-ineffective-attrs

[yeonjuan]

Checklist

• Addresses an existing open issue: fixes [FEATURE] Add no-ineffective-attrs rule #346

Description

[Copilot]

Pull Request Overview

This PR introduces a new ESLint rule called no-ineffective-attrs that detects HTML attributes that have no effect in their current context. The rule helps identify potential errors or unnecessary code by flagging attributes like multiple on text inputs, defer on inline scripts, or download without href.

• Adds a new ESLint rule implementation with comprehensive validation logic
• Includes extensive test coverage for both regular HTML and template literals
• Provides documentation with clear examples of correct and incorrect usage

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/eslint-plugin/lib/rules/no-ineffective-attrs.js	Core rule implementation that checks for ineffective HTML attributes across different element types
packages/eslint-plugin/tests/rules/no-ineffective-attrs.test.js	Comprehensive test suite covering valid and invalid attribute combinations
packages/eslint-plugin/lib/rules/utils/node.js	Adds utility function hasAttr for checking attribute presence
packages/eslint-plugin/lib/rules/index.js	Registers the new rule in the rules index
docs/rules/no-ineffective-attrs.md	User documentation with usage examples and rule explanation
.cspell.json	Adds spell check exceptions for HTML attribute values

[Copilot]

The magic string "text" is used as a default input type. Consider extracting this as a named constant to improve maintainability and reduce duplication (it appears on lines 32, 49, and 58).

Suggested change

	const type = getAttrValue(node, "type") || "text";
	const type = getAttrValue(node, "type") || DEFAULT_INPUT_TYPE;

[Copilot]

The logic in the ScriptTag visitor is nearly identical to the Tag visitor (lines 126-146). Consider extracting the common attribute checking logic into a shared helper function to reduce code duplication.

Suggested change

	const tagCheckers = checkersByTag[node.name];
	if (!tagCheckers) return;
	for (const check of tagCheckers) {
	for (const attr of node.attributes) {
	if (attr.type !== "Attribute") continue;
	if (attr.key.value !== check.attr) continue;
	if (check.when(node)) {
	context.report({
	loc: attr.loc,
	messageId: "ineffective",
	data: {
	message: check.message,
	},
	});
	}
	}
	}
	},
	/**
	* @param {ScriptTag} node
	*/
	ScriptTag(node) {
	const scriptCheckers = checkersByTag.script;
	if (!scriptCheckers) return;
	for (const check of scriptCheckers) {
	for (const attr of node.attributes) {
	if (attr.type !== "Attribute") continue;
	if (attr.key.value !== check.attr) continue;
	if (check.when(node)) {
	context.report({
	loc: attr.loc,
	messageId: "ineffective",
	data: {
	message: check.message,
	},
	});
	}
	}
	}
	checkIneffectiveAttrs(node, checkersByTag[node.name], context);
	},
	/**
	* @param {ScriptTag} node
	*/
	ScriptTag(node) {
	checkIneffectiveAttrs(node, checkersByTag.script, context);

[Copilot]

The array of input types that don't support 'multiple' should be extracted as a constant. This improves maintainability and makes it easier to update the list if HTML specifications change.

Suggested change

	return [
	"text",
	"password",
	"radio",
	"checkbox",
	"image",
	"hidden",
	"reset",
	"button",
	].includes(type);
	return INPUT_TYPES_WITHOUT_MULTIPLE.includes(type);

[Copilot]

The array of input types that don't support 'readonly' should be extracted as a constant for better maintainability and consistency with other type checking logic.

Suggested change

	return ["checkbox", "radio", "file", "range", "color"].includes(type);
	return INPUT_TYPES_WITHOUT_READONLY.includes(type);

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.56%. Comparing base (9d00cec) to head (286ba84).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #399      +/-   ##
==========================================
+ Coverage   98.53%   98.56%   +0.02%     
==========================================
  Files          82       83       +1     
  Lines        2658     2712      +54     
  Branches      736      752      +16     
==========================================
+ Hits         2619     2673      +54     
  Misses         39       39              

Flag	Coverage Δ
unittest	98.56% <100.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/eslint-plugin/lib/rules/index.js	100.00% <100.00%> (ø)
...es/eslint-plugin/lib/rules/no-ineffective-attrs.js	100.00% <100.00%> (ø)
packages/eslint-plugin/lib/rules/utils/node.js	95.77% <100.00%> (+0.18%)	⬆️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.