1 | /**
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2 | * @fileoverview Rule to flag non-camelcased identifiers
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3 | * @author Nicholas C. Zakas
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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 | //------------------------------------------------------------------------------
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9 | // Rule Definition
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10 | //------------------------------------------------------------------------------
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11 |
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12 | module.exports = {
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13 | meta: {
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14 | docs: {
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15 | description: "enforce camelcase naming convention",
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16 | category: "Stylistic Issues",
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17 | recommended: false,
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18 | url: "https://eslint.org/docs/rules/camelcase"
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19 | },
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20 |
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21 | schema: [
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22 | {
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23 | type: "object",
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24 | properties: {
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25 | properties: {
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26 | enum: ["always", "never"]
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27 | }
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28 | },
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29 | additionalProperties: false
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30 | }
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31 | ],
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32 |
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33 | messages: {
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34 | notCamelCase: "Identifier '{{name}}' is not in camel case."
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35 | }
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36 | },
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37 |
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38 | create(context) {
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39 |
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40 | //--------------------------------------------------------------------------
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41 | // Helpers
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42 | //--------------------------------------------------------------------------
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43 |
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44 | // contains reported nodes to avoid reporting twice on destructuring with shorthand notation
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45 | const reported = [];
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46 | const ALLOWED_PARENT_TYPES = new Set(["CallExpression", "NewExpression"]);
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47 |
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48 | /**
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49 | * Checks if a string contains an underscore and isn't all upper-case
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50 | * @param {string} name The string to check.
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51 | * @returns {boolean} if the string is underscored
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52 | * @private
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53 | */
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54 | function isUnderscored(name) {
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55 |
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56 | // if there's an underscore, it might be A_CONSTANT, which is okay
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57 | return name.indexOf("_") > -1 && name !== name.toUpperCase();
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58 | }
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59 |
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60 | /**
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61 | * Reports an AST node as a rule violation.
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62 | * @param {ASTNode} node The node to report.
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63 | * @returns {void}
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64 | * @private
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65 | */
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66 | function report(node) {
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67 | if (reported.indexOf(node) < 0) {
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68 | reported.push(node);
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69 | context.report({ node, messageId: "notCamelCase", data: { name: node.name } });
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70 | }
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71 | }
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72 |
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73 | const options = context.options[0] || {};
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74 | let properties = options.properties || "";
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75 |
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76 | if (properties !== "always" && properties !== "never") {
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77 | properties = "always";
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78 | }
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79 |
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80 | return {
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81 |
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82 | Identifier(node) {
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83 |
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84 | /*
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85 | * Leading and trailing underscores are commonly used to flag
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86 | * private/protected identifiers, strip them
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87 | */
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88 | const name = node.name.replace(/^_+|_+$/g, ""),
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89 | effectiveParent = (node.parent.type === "MemberExpression") ? node.parent.parent : node.parent;
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90 |
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91 | // MemberExpressions get special rules
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92 | if (node.parent.type === "MemberExpression") {
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93 |
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94 | // "never" check properties
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95 | if (properties === "never") {
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96 | return;
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97 | }
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98 |
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99 | // Always report underscored object names
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100 | if (node.parent.object.type === "Identifier" && node.parent.object.name === node.name && isUnderscored(name)) {
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101 | report(node);
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102 |
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103 | // Report AssignmentExpressions only if they are the left side of the assignment
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104 | } else if (effectiveParent.type === "AssignmentExpression" && isUnderscored(name) && (effectiveParent.right.type !== "MemberExpression" || effectiveParent.left.type === "MemberExpression" && effectiveParent.left.property.name === node.name)) {
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105 | report(node);
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106 | }
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107 |
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108 | /*
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109 | * Properties have their own rules, and
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110 | * AssignmentPattern nodes can be treated like Properties:
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111 | * e.g.: const { no_camelcased = false } = bar;
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112 | */
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113 | } else if (node.parent.type === "Property" || node.parent.type === "AssignmentPattern") {
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114 |
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115 | if (node.parent.parent && node.parent.parent.type === "ObjectPattern") {
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116 |
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117 | if (node.parent.shorthand && node.parent.value.left && isUnderscored(name)) {
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118 |
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119 | report(node);
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120 | }
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121 |
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122 | // prevent checking righthand side of destructured object
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123 | if (node.parent.key === node && node.parent.value !== node) {
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124 | return;
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125 | }
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126 |
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127 | if (node.parent.value.name && isUnderscored(name)) {
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128 | report(node);
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129 | }
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130 | }
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131 |
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132 | // "never" check properties
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133 | if (properties === "never") {
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134 | return;
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135 | }
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136 |
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137 | // don't check right hand side of AssignmentExpression to prevent duplicate warnings
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138 | if (isUnderscored(name) && !ALLOWED_PARENT_TYPES.has(effectiveParent.type) && !(node.parent.right === node)) {
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139 | report(node);
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140 | }
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141 |
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142 | // Check if it's an import specifier
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143 | } else if (["ImportSpecifier", "ImportNamespaceSpecifier", "ImportDefaultSpecifier"].indexOf(node.parent.type) >= 0) {
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144 |
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145 | // Report only if the local imported identifier is underscored
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146 | if (node.parent.local && node.parent.local.name === node.name && isUnderscored(name)) {
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147 | report(node);
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148 | }
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149 |
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150 | // Report anything that is underscored that isn't a CallExpression
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151 | } else if (isUnderscored(name) && !ALLOWED_PARENT_TYPES.has(effectiveParent.type)) {
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152 | report(node);
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153 | }
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154 | }
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155 |
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156 | };
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157 |
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158 | }
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159 | };
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