routie dev init since i didn't adhere to any proper guidance up until now

2026-04-29 22:27:29 -06:00
commit e1dabb71e2
15301 changed files with 3562618 additions and 0 deletions
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+import {getNegativeIndexLengthNode, removeLengthNode} from './shared/negative-index.js';
+import typedArray from './shared/typed-array.js';
+import {isEmptyArrayExpression, isLiteral} from './ast/index.js';
+
+const MESSAGE_ID = 'prefer-negative-index';
+const messages = {
+	[MESSAGE_ID]: 'Prefer negative index over length minus index for `{{method}}`.',
+};
+
+const methods = new Map([
+	[
+		'slice',
+		{
+			argumentsIndexes: [0, 1],
+			supportObjects: new Set([
+				'Array',
+				'String',
+				'ArrayBuffer',
+				...typedArray,
+				// `{Blob,File}#slice()` are not generally used
+				// 'Blob'
+				// 'File'
+			]),
+		},
+	],
+	[
+		'subarray',
+		{
+			argumentsIndexes: [0, 1],
+			supportObjects: new Set(typedArray),
+		},
+	],
+	[
+		'splice',
+		{
+			argumentsIndexes: [0],
+			supportObjects: new Set([
+				'Array',
+			]),
+		},
+	],
+	[
+		'toSpliced',
+		{
+			argumentsIndexes: [0],
+			supportObjects: new Set([
+				'Array',
+			]),
+		},
+	],
+	[
+		'at',
+		{
+			argumentsIndexes: [0],
+			supportObjects: new Set([
+				'Array',
+				'String',
+				...typedArray,
+			]),
+		},
+	],
+	[
+		'with',
+		{
+			argumentsIndexes: [0],
+			supportObjects: new Set([
+				'Array',
+				...typedArray,
+			]),
+		},
+	],
+]);
+
+const getMemberName = node => {
+	const {type, property} = node;
+
+	if (
+		type === 'MemberExpression'
+		&& property.type === 'Identifier'
+	) {
+		return property.name;
+	}
+};
+
+function parse(node) {
+	const {callee, arguments: originalArguments} = node;
+
+	let method = callee.property.name;
+	let target = callee.object;
+	let argumentsNodes = originalArguments;
+
+	if (methods.has(method)) {
+		return {
+			method,
+			target,
+			argumentsNodes,
+		};
+	}
+
+	if (method !== 'call' && method !== 'apply') {
+		return;
+	}
+
+	const isApply = method === 'apply';
+
+	method = getMemberName(callee.object);
+
+	if (!methods.has(method)) {
+		return;
+	}
+
+	const {supportObjects} = methods.get(method);
+
+	const parentCallee = callee.object.object;
+
+	if (
+		// `[].{slice,splice,toSpliced,at,with}`
+		isEmptyArrayExpression(parentCallee)
+		// `''.slice`
+		|| (
+			method === 'slice'
+			&& isLiteral(parentCallee, '')
+		)
+		// {Array,String...}.prototype.slice
+		// Array.prototype.splice
+		|| (
+			getMemberName(parentCallee) === 'prototype'
+			&& parentCallee.object.type === 'Identifier'
+			&& supportObjects.has(parentCallee.object.name)
+		)
+	) {
+		[target] = originalArguments;
+
+		if (isApply) {
+			const [, secondArgument] = originalArguments;
+			if (!secondArgument || secondArgument.type !== 'ArrayExpression') {
+				return;
+			}
+
+			argumentsNodes = secondArgument.elements;
+		} else {
+			argumentsNodes = originalArguments.slice(1);
+		}
+
+		return {
+			method,
+			target,
+			argumentsNodes,
+		};
+	}
+}
+
+/** @param {import('eslint').Rule.RuleContext} context */
+const create = context => {
+	context.on('CallExpression', node => {
+		if (node.callee.type !== 'MemberExpression') {
+			return;
+		}
+
+		const parsed = parse(node);
+
+		if (!parsed) {
+			return;
+		}
+
+		const {
+			method,
+			target,
+			argumentsNodes,
+		} = parsed;
+
+		const {argumentsIndexes} = methods.get(method);
+		const removableNodes = argumentsIndexes
+			.map(index => getNegativeIndexLengthNode(argumentsNodes[index], target))
+			.filter(Boolean);
+
+		if (removableNodes.length === 0) {
+			return;
+		}
+
+		return {
+			node,
+			messageId: MESSAGE_ID,
+			data: {method},
+			* fix(fixer) {
+				for (const node of removableNodes) {
+					yield removeLengthNode(node, fixer, context);
+				}
+			},
+		};
+	});
+};
+
+/** @type {import('eslint').Rule.RuleModule} */
+const config = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			description: 'Prefer negative index over `.length - index` when possible.',
+			recommended: 'unopinionated',
+		},
+		fixable: 'code',
+		messages,
+	},
+};
+
+export default config;