Add components

slider/node_modules/eslint/lib/rules/use-isnan.js

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+/**
+ * @fileoverview Rule to flag comparisons to the value NaN
+ * @author James Allardice
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Determines if the given node is a NaN `Identifier` node.
+ * @param {ASTNode|null} node The node to check.
+ * @returns {boolean} `true` if the node is 'NaN' identifier.
+ */
+function isNaNIdentifier(node) {
+	if (!node) {
+		return false;
+	}
+
+	const nodeToCheck =
+		node.type === "SequenceExpression" ? node.expressions.at(-1) : node;
+
+	return (
+		astUtils.isSpecificId(nodeToCheck, "NaN") ||
+		astUtils.isSpecificMemberAccess(nodeToCheck, "Number", "NaN")
+	);
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../types').Rule.RuleModule} */
+module.exports = {
+	meta: {
+		hasSuggestions: true,
+		type: "problem",
+
+		docs: {
+			description: "Require calls to `isNaN()` when checking for `NaN`",
+			recommended: true,
+			url: "https://eslint.org/docs/latest/rules/use-isnan",
+		},
+
+		schema: [
+			{
+				type: "object",
+				properties: {
+					enforceForSwitchCase: {
+						type: "boolean",
+					},
+					enforceForIndexOf: {
+						type: "boolean",
+					},
+				},
+				additionalProperties: false,
+			},
+		],
+
+		defaultOptions: [
+			{
+				enforceForIndexOf: false,
+				enforceForSwitchCase: true,
+			},
+		],
+
+		messages: {
+			comparisonWithNaN: "Use the isNaN function to compare with NaN.",
+			switchNaN:
+				"'switch(NaN)' can never match a case clause. Use Number.isNaN instead of the switch.",
+			caseNaN:
+				"'case NaN' can never match. Use Number.isNaN before the switch.",
+			indexOfNaN:
+				"Array prototype method '{{ methodName }}' cannot find NaN.",
+			replaceWithIsNaN: "Replace with Number.isNaN.",
+			replaceWithCastingAndIsNaN:
+				"Replace with Number.isNaN and cast to a Number.",
+			replaceWithFindIndex:
+				"Replace with Array.prototype.{{ methodName }}.",
+		},
+	},
+
+	create(context) {
+		const [{ enforceForIndexOf, enforceForSwitchCase }] = context.options;
+		const sourceCode = context.sourceCode;
+
+		const fixableOperators = new Set(["==", "===", "!=", "!=="]);
+		const castableOperators = new Set(["==", "!="]);
+
+		/**
+		 * Get a fixer for a binary expression that compares to NaN.
+		 * @param  {ASTNode} node The node to fix.
+		 * @param {function(string): string} wrapValue A function that wraps the compared value with a fix.
+		 * @returns {function(Fixer): Fix} The fixer function.
+		 */
+		function getBinaryExpressionFixer(node, wrapValue) {
+			return fixer => {
+				const comparedValue = isNaNIdentifier(node.left)
+					? node.right
+					: node.left;
+				const shouldWrap = comparedValue.type === "SequenceExpression";
+				const shouldNegate = node.operator[0] === "!";
+
+				const negation = shouldNegate ? "!" : "";
+				let comparedValueText = sourceCode.getText(comparedValue);
+
+				if (shouldWrap) {
+					comparedValueText = `(${comparedValueText})`;
+				}
+
+				const fixedValue = wrapValue(comparedValueText);
+
+				return fixer.replaceText(node, `${negation}${fixedValue}`);
+			};
+		}
+
+		/**
+		 * Checks the given `BinaryExpression` node for `foo === NaN` and other comparisons.
+		 * @param {ASTNode} node The node to check.
+		 * @returns {void}
+		 */
+		function checkBinaryExpression(node) {
+			if (
+				/^(?:[<>]|[!=]=)=?$/u.test(node.operator) &&
+				(isNaNIdentifier(node.left) || isNaNIdentifier(node.right))
+			) {
+				const suggestedFixes = [];
+				const NaNNode = isNaNIdentifier(node.left)
+					? node.left
+					: node.right;
+
+				const isSequenceExpression =
+					NaNNode.type === "SequenceExpression";
+				const isSuggestable =
+					fixableOperators.has(node.operator) &&
+					!isSequenceExpression;
+				const isCastable = castableOperators.has(node.operator);
+
+				if (isSuggestable) {
+					suggestedFixes.push({
+						messageId: "replaceWithIsNaN",
+						fix: getBinaryExpressionFixer(
+							node,
+							value => `Number.isNaN(${value})`,
+						),
+					});
+
+					if (isCastable) {
+						suggestedFixes.push({
+							messageId: "replaceWithCastingAndIsNaN",
+							fix: getBinaryExpressionFixer(
+								node,
+								value => `Number.isNaN(Number(${value}))`,
+							),
+						});
+					}
+				}
+
+				context.report({
+					node,
+					messageId: "comparisonWithNaN",
+					suggest: suggestedFixes,
+				});
+			}
+		}
+
+		/**
+		 * Checks the discriminant and all case clauses of the given `SwitchStatement` node for `switch(NaN)` and `case NaN:`
+		 * @param {ASTNode} node The node to check.
+		 * @returns {void}
+		 */
+		function checkSwitchStatement(node) {
+			if (isNaNIdentifier(node.discriminant)) {
+				context.report({ node, messageId: "switchNaN" });
+			}
+
+			for (const switchCase of node.cases) {
+				if (isNaNIdentifier(switchCase.test)) {
+					context.report({ node: switchCase, messageId: "caseNaN" });
+				}
+			}
+		}
+
+		/**
+		 * Checks the given `CallExpression` node for `.indexOf(NaN)` and `.lastIndexOf(NaN)`.
+		 * @param {ASTNode} node The node to check.
+		 * @returns {void}
+		 */
+		function checkCallExpression(node) {
+			const callee = astUtils.skipChainExpression(node.callee);
+
+			if (callee.type === "MemberExpression") {
+				const methodName = astUtils.getStaticPropertyName(callee);
+
+				if (
+					(methodName === "indexOf" ||
+						methodName === "lastIndexOf") &&
+					node.arguments.length <= 2 &&
+					isNaNIdentifier(node.arguments[0])
+				) {
+					/*
+					 * To retain side effects, it's essential to address `NaN` beforehand, which
+					 * is not possible with fixes like `arr.findIndex(Number.isNaN)`.
+					 */
+					const isSuggestable =
+						node.arguments[0].type !== "SequenceExpression" &&
+						!node.arguments[1];
+					const suggestedFixes = [];
+
+					if (isSuggestable) {
+						const shouldWrap = callee.computed;
+						const findIndexMethod =
+							methodName === "indexOf"
+								? "findIndex"
+								: "findLastIndex";
+						const propertyName = shouldWrap
+							? `"${findIndexMethod}"`
+							: findIndexMethod;
+
+						suggestedFixes.push({
+							messageId: "replaceWithFindIndex",
+							data: { methodName: findIndexMethod },
+							fix: fixer => [
+								fixer.replaceText(
+									callee.property,
+									propertyName,
+								),
+								fixer.replaceText(
+									node.arguments[0],
+									"Number.isNaN",
+								),
+							],
+						});
+					}
+
+					context.report({
+						node,
+						messageId: "indexOfNaN",
+						data: { methodName },
+						suggest: suggestedFixes,
+					});
+				}
+			}
+		}
+
+		const listeners = {
+			BinaryExpression: checkBinaryExpression,
+		};
+
+		if (enforceForSwitchCase) {
+			listeners.SwitchStatement = checkSwitchStatement;
+		}
+
+		if (enforceForIndexOf) {
+			listeners.CallExpression = checkCallExpression;
+		}
+
+		return listeners;
+	},
+};