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- /**
- * @fileoverview Rule to warn about using dot notation instead of square bracket notation when possible.
- * @author Josh Perez
- */
- "use strict";
- //------------------------------------------------------------------------------
- // Requirements
- //------------------------------------------------------------------------------
- const astUtils = require("./utils/ast-utils");
- const keywords = require("./utils/keywords");
- //------------------------------------------------------------------------------
- // Rule Definition
- //------------------------------------------------------------------------------
- const validIdentifier = /^[a-zA-Z_$][a-zA-Z0-9_$]*$/u;
- // `null` literal must be handled separately.
- const literalTypesToCheck = new Set(["string", "boolean"]);
- /** @type {import('../shared/types').Rule} */
- module.exports = {
- meta: {
- type: "suggestion",
- docs: {
- description: "Enforce dot notation whenever possible",
- recommended: false,
- url: "https://eslint.org/docs/rules/dot-notation"
- },
- schema: [
- {
- type: "object",
- properties: {
- allowKeywords: {
- type: "boolean",
- default: true
- },
- allowPattern: {
- type: "string",
- default: ""
- }
- },
- additionalProperties: false
- }
- ],
- fixable: "code",
- messages: {
- useDot: "[{{key}}] is better written in dot notation.",
- useBrackets: ".{{key}} is a syntax error."
- }
- },
- create(context) {
- const options = context.options[0] || {};
- const allowKeywords = options.allowKeywords === void 0 || options.allowKeywords;
- const sourceCode = context.getSourceCode();
- let allowPattern;
- if (options.allowPattern) {
- allowPattern = new RegExp(options.allowPattern, "u");
- }
- /**
- * Check if the property is valid dot notation
- * @param {ASTNode} node The dot notation node
- * @param {string} value Value which is to be checked
- * @returns {void}
- */
- function checkComputedProperty(node, value) {
- if (
- validIdentifier.test(value) &&
- (allowKeywords || !keywords.includes(String(value))) &&
- !(allowPattern && allowPattern.test(value))
- ) {
- const formattedValue = node.property.type === "Literal" ? JSON.stringify(value) : `\`${value}\``;
- context.report({
- node: node.property,
- messageId: "useDot",
- data: {
- key: formattedValue
- },
- *fix(fixer) {
- const leftBracket = sourceCode.getTokenAfter(node.object, astUtils.isOpeningBracketToken);
- const rightBracket = sourceCode.getLastToken(node);
- const nextToken = sourceCode.getTokenAfter(node);
- // Don't perform any fixes if there are comments inside the brackets.
- if (sourceCode.commentsExistBetween(leftBracket, rightBracket)) {
- return;
- }
- // Replace the brackets by an identifier.
- if (!node.optional) {
- yield fixer.insertTextBefore(
- leftBracket,
- astUtils.isDecimalInteger(node.object) ? " ." : "."
- );
- }
- yield fixer.replaceTextRange(
- [leftBracket.range[0], rightBracket.range[1]],
- value
- );
- // Insert a space after the property if it will be connected to the next token.
- if (
- nextToken &&
- rightBracket.range[1] === nextToken.range[0] &&
- !astUtils.canTokensBeAdjacent(String(value), nextToken)
- ) {
- yield fixer.insertTextAfter(node, " ");
- }
- }
- });
- }
- }
- return {
- MemberExpression(node) {
- if (
- node.computed &&
- node.property.type === "Literal" &&
- (literalTypesToCheck.has(typeof node.property.value) || astUtils.isNullLiteral(node.property))
- ) {
- checkComputedProperty(node, node.property.value);
- }
- if (
- node.computed &&
- node.property.type === "TemplateLiteral" &&
- node.property.expressions.length === 0
- ) {
- checkComputedProperty(node, node.property.quasis[0].value.cooked);
- }
- if (
- !allowKeywords &&
- !node.computed &&
- node.property.type === "Identifier" &&
- keywords.includes(String(node.property.name))
- ) {
- context.report({
- node: node.property,
- messageId: "useBrackets",
- data: {
- key: node.property.name
- },
- *fix(fixer) {
- const dotToken = sourceCode.getTokenBefore(node.property);
- // A statement that starts with `let[` is parsed as a destructuring variable declaration, not a MemberExpression.
- if (node.object.type === "Identifier" && node.object.name === "let" && !node.optional) {
- return;
- }
- // Don't perform any fixes if there are comments between the dot and the property name.
- if (sourceCode.commentsExistBetween(dotToken, node.property)) {
- return;
- }
- // Replace the identifier to brackets.
- if (!node.optional) {
- yield fixer.remove(dotToken);
- }
- yield fixer.replaceText(node.property, `["${node.property.name}"]`);
- }
- });
- }
- }
- };
- }
- };
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