Add components

slider/node_modules/eslint/lib/rules/no-sequences.js

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+/**
+ * @fileoverview Rule to flag use of comma operator
+ * @author Brandon Mills
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../types').Rule.RuleModule} */
+module.exports = {
+	meta: {
+		type: "suggestion",
+
+		docs: {
+			description: "Disallow comma operators",
+			recommended: false,
+			url: "https://eslint.org/docs/latest/rules/no-sequences",
+		},
+
+		schema: [
+			{
+				type: "object",
+				properties: {
+					allowInParentheses: {
+						type: "boolean",
+					},
+				},
+				additionalProperties: false,
+			},
+		],
+
+		defaultOptions: [
+			{
+				allowInParentheses: true,
+			},
+		],
+
+		messages: {
+			unexpectedCommaExpression: "Unexpected use of comma operator.",
+		},
+	},
+
+	create(context) {
+		const [{ allowInParentheses }] = context.options;
+		const sourceCode = context.sourceCode;
+
+		/**
+		 * Parts of the grammar that are required to have parens.
+		 */
+		const parenthesized = {
+			DoWhileStatement: "test",
+			IfStatement: "test",
+			SwitchStatement: "discriminant",
+			WhileStatement: "test",
+			WithStatement: "object",
+			ArrowFunctionExpression: "body",
+
+			/*
+			 * Omitting CallExpression - commas are parsed as argument separators
+			 * Omitting NewExpression - commas are parsed as argument separators
+			 * Omitting ForInStatement - parts aren't individually parenthesised
+			 * Omitting ForStatement - parts aren't individually parenthesised
+			 */
+		};
+
+		/**
+		 * Determines whether a node is required by the grammar to be wrapped in
+		 * parens, e.g. the test of an if statement.
+		 * @param {ASTNode} node The AST node
+		 * @returns {boolean} True if parens around node belong to parent node.
+		 */
+		function requiresExtraParens(node) {
+			return (
+				node.parent &&
+				parenthesized[node.parent.type] &&
+				node === node.parent[parenthesized[node.parent.type]]
+			);
+		}
+
+		/**
+		 * Check if a node is wrapped in parens.
+		 * @param {ASTNode} node The AST node
+		 * @returns {boolean} True if the node has a paren on each side.
+		 */
+		function isParenthesised(node) {
+			return astUtils.isParenthesised(sourceCode, node);
+		}
+
+		/**
+		 * Check if a node is wrapped in two levels of parens.
+		 * @param {ASTNode} node The AST node
+		 * @returns {boolean} True if two parens surround the node on each side.
+		 */
+		function isParenthesisedTwice(node) {
+			const previousToken = sourceCode.getTokenBefore(node, 1),
+				nextToken = sourceCode.getTokenAfter(node, 1);
+
+			return (
+				isParenthesised(node) &&
+				previousToken &&
+				nextToken &&
+				astUtils.isOpeningParenToken(previousToken) &&
+				previousToken.range[1] <= node.range[0] &&
+				astUtils.isClosingParenToken(nextToken) &&
+				nextToken.range[0] >= node.range[1]
+			);
+		}
+
+		return {
+			SequenceExpression(node) {
+				// Always allow sequences in for statement update
+				if (
+					node.parent.type === "ForStatement" &&
+					(node === node.parent.init || node === node.parent.update)
+				) {
+					return;
+				}
+
+				// Wrapping a sequence in extra parens indicates intent
+				if (allowInParentheses) {
+					if (requiresExtraParens(node)) {
+						if (isParenthesisedTwice(node)) {
+							return;
+						}
+					} else {
+						if (isParenthesised(node)) {
+							return;
+						}
+					}
+				}
+
+				const firstCommaToken = sourceCode.getTokenAfter(
+					node.expressions[0],
+					astUtils.isCommaToken,
+				);
+
+				context.report({
+					node,
+					loc: firstCommaToken.loc,
+					messageId: "unexpectedCommaExpression",
+				});
+			},
+		};
+	},
+};