eslint-plugin-unicorn/rules/no-magic-array-flat-depth.js

More than 300 powerful ESLint rules

import {isMethodCall} from './ast/index.js';
import {
	getCallExpressionTokens,
	getStaticNumberValue,
	hasNonDirectiveComment,
	shouldSkipKnownNonArrayReceiver,
} from './utils/index.js';

const MESSAGE_ID = 'no-magic-array-flat-depth';
const messages = {
	[MESSAGE_ID]: 'Magic number as depth is not allowed.',
};

/**
@param {import('eslint').Rule.RuleContext} context
*/
const create = context => {
	context.on('CallExpression', callExpression => {
		if (!isMethodCall(callExpression, {
			method: 'flat',
			argumentsLength: 1,
			optionalCall: false,
		})) {
			return;
		}

		const [depth] = callExpression.arguments;

		// `getStaticNumberValue()` also unwraps a `-2`/`+2` unary expression and TypeScript wrappers
		const depthValue = getStaticNumberValue(depth);

		if (typeof depthValue !== 'number' || depthValue === 1) {
			return;
		}

		const {sourceCode} = context;
		const {
			openingParenthesisToken,
			closingParenthesisToken,
		} = getCallExpressionTokens(callExpression, context);
		if (
			hasNonDirectiveComment(context, [sourceCode.getRange(openingParenthesisToken)[1], sourceCode.getRange(closingParenthesisToken)[0]])
			|| shouldSkipKnownNonArrayReceiver(callExpression.callee.object, context)
		) {
			return;
		}

		return {
			node: depth,
			messageId: MESSAGE_ID,
		};
	});
};

/**
@type {import('eslint').Rule.RuleModule}
*/
const config = {
	create,
	meta: {
		type: 'suggestion',
		docs: {
			description: 'Disallow a magic number as the `depth` argument in `Array#flat(…).`',
			recommended: 'unopinionated',
		},
		messages,
		languages: [
			'js/js',
		],
	},
};

export default config;