/** * @fileoverview Rule to flag use of an lexical declarations inside a case clause * @author Erik Arvidsson */ "use strict"; //------------------------------------------------------------------------------ // Rule Definition //------------------------------------------------------------------------------ /** @type {import('../types').Rule.RuleModule} */ module.exports = { meta: { type: "suggestion", docs: { description: "Disallow lexical declarations in case clauses", recommended: true, url: "https://eslint.org/docs/latest/rules/no-case-declarations", }, hasSuggestions: true, schema: [], messages: { addBrackets: "Add {} brackets around the case block.", unexpected: "Unexpected lexical declaration in case block.", }, }, create(context) { /** * Checks whether or not a node is a lexical declaration. * @param {ASTNode} node A direct child statement of a switch case. * @returns {boolean} Whether or not the node is a lexical declaration. */ function isLexicalDeclaration(node) { switch (node.type) { case "FunctionDeclaration": case "ClassDeclaration": return true; case "VariableDeclaration": return node.kind !== "var"; default: return false; } } return { SwitchCase(node) { for (let i = 0; i < node.consequent.length; i++) { const statement = node.consequent[i]; if (isLexicalDeclaration(statement)) { context.report({ node: statement, messageId: "unexpected", suggest: [ { messageId: "addBrackets", fix: fixer => [ fixer.insertTextBefore( node.consequent[0], "{ ", ), fixer.insertTextAfter( node.consequent.at(-1), " }", ), ], }, ], }); } } }, }; }, };