1 | /**
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2 | * @fileoverview Rule to warn about using dot notation instead of square bracket notation when possible.
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3 | * @author Josh Perez
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4 | */
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5 | ;
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6 |
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7 | //------------------------------------------------------------------------------
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8 | // Requirements
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9 | //------------------------------------------------------------------------------
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10 |
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11 | const astUtils = require("./utils/ast-utils");
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12 | const keywords = require("./utils/keywords");
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13 |
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14 | //------------------------------------------------------------------------------
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15 | // Rule Definition
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16 | //------------------------------------------------------------------------------
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17 |
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18 | const validIdentifier = /^[a-zA-Z_$][a-zA-Z0-9_$]*$/u;
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19 |
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20 | // `null` literal must be handled separately.
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21 | const literalTypesToCheck = new Set(["string", "boolean"]);
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22 |
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23 | module.exports = {
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24 | meta: {
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25 | type: "suggestion",
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26 |
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27 | docs: {
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28 | description: "enforce dot notation whenever possible",
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29 | category: "Best Practices",
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30 | recommended: false,
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31 | url: "https://eslint.org/docs/rules/dot-notation"
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32 | },
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33 |
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34 | schema: [
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35 | {
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36 | type: "object",
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37 | properties: {
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38 | allowKeywords: {
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39 | type: "boolean",
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40 | default: true
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41 | },
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42 | allowPattern: {
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43 | type: "string",
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44 | default: ""
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45 | }
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46 | },
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47 | additionalProperties: false
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48 | }
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49 | ],
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50 |
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51 | fixable: "code",
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52 |
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53 | messages: {
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54 | useDot: "[{{key}}] is better written in dot notation.",
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55 | useBrackets: ".{{key}} is a syntax error."
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56 | }
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57 | },
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58 |
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59 | create(context) {
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60 | const options = context.options[0] || {};
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61 | const allowKeywords = options.allowKeywords === void 0 || options.allowKeywords;
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62 | const sourceCode = context.getSourceCode();
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63 |
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64 | let allowPattern;
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65 |
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66 | if (options.allowPattern) {
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67 | allowPattern = new RegExp(options.allowPattern, "u");
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68 | }
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69 |
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70 | /**
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71 | * Check if the property is valid dot notation
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72 | * @param {ASTNode} node The dot notation node
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73 | * @param {string} value Value which is to be checked
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74 | * @returns {void}
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75 | */
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76 | function checkComputedProperty(node, value) {
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77 | if (
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78 | validIdentifier.test(value) &&
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79 | (allowKeywords || keywords.indexOf(String(value)) === -1) &&
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80 | !(allowPattern && allowPattern.test(value))
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81 | ) {
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82 | const formattedValue = node.property.type === "Literal" ? JSON.stringify(value) : `\`${value}\``;
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83 |
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84 | context.report({
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85 | node: node.property,
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86 | messageId: "useDot",
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87 | data: {
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88 | key: formattedValue
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89 | },
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90 | *fix(fixer) {
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91 | const leftBracket = sourceCode.getTokenAfter(node.object, astUtils.isOpeningBracketToken);
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92 | const rightBracket = sourceCode.getLastToken(node);
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93 | const nextToken = sourceCode.getTokenAfter(node);
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94 |
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95 | // Don't perform any fixes if there are comments inside the brackets.
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96 | if (sourceCode.commentsExistBetween(leftBracket, rightBracket)) {
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97 | return; // eslint-disable-line eslint-plugin/fixer-return -- false positive
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98 | }
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99 |
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100 | // Replace the brackets by an identifier.
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101 | if (!node.optional) {
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102 | yield fixer.insertTextBefore(
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103 | leftBracket,
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104 | astUtils.isDecimalInteger(node.object) ? " ." : "."
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105 | );
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106 | }
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107 | yield fixer.replaceTextRange(
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108 | [leftBracket.range[0], rightBracket.range[1]],
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109 | value
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110 | );
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111 |
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112 | // Insert a space after the property if it will be connected to the next token.
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113 | if (
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114 | nextToken &&
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115 | rightBracket.range[1] === nextToken.range[0] &&
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116 | !astUtils.canTokensBeAdjacent(String(value), nextToken)
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117 | ) {
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118 | yield fixer.insertTextAfter(node, " ");
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119 | }
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120 | }
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121 | });
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122 | }
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123 | }
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124 |
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125 | return {
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126 | MemberExpression(node) {
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127 | if (
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128 | node.computed &&
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129 | node.property.type === "Literal" &&
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130 | (literalTypesToCheck.has(typeof node.property.value) || astUtils.isNullLiteral(node.property))
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131 | ) {
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132 | checkComputedProperty(node, node.property.value);
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133 | }
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134 | if (
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135 | node.computed &&
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136 | node.property.type === "TemplateLiteral" &&
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137 | node.property.expressions.length === 0
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138 | ) {
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139 | checkComputedProperty(node, node.property.quasis[0].value.cooked);
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140 | }
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141 | if (
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142 | !allowKeywords &&
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143 | !node.computed &&
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144 | keywords.indexOf(String(node.property.name)) !== -1
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145 | ) {
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146 | context.report({
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147 | node: node.property,
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148 | messageId: "useBrackets",
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149 | data: {
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150 | key: node.property.name
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151 | },
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152 | *fix(fixer) {
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153 | const dotToken = sourceCode.getTokenBefore(node.property);
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154 |
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155 | // A statement that starts with `let[` is parsed as a destructuring variable declaration, not a MemberExpression.
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156 | if (node.object.type === "Identifier" && node.object.name === "let" && !node.optional) {
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157 | return; // eslint-disable-line eslint-plugin/fixer-return -- false positive
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158 | }
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159 |
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160 | // Don't perform any fixes if there are comments between the dot and the property name.
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161 | if (sourceCode.commentsExistBetween(dotToken, node.property)) {
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162 | return; // eslint-disable-line eslint-plugin/fixer-return -- false positive
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163 | }
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164 |
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165 | // Replace the identifier to brackets.
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166 | if (!node.optional) {
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167 | yield fixer.remove(dotToken);
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168 | }
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169 | yield fixer.replaceText(node.property, `["${node.property.name}"]`);
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170 | }
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171 | });
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172 | }
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173 | }
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174 | };
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175 | }
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176 | };
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