1 | /**
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2 | * @fileoverview Rule to flag use of console object
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3 | * @author Nicholas C. Zakas
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4 | */
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5 |
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6 | "use strict";
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7 |
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8 | //------------------------------------------------------------------------------
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9 | // Requirements
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10 | //------------------------------------------------------------------------------
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11 |
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12 | const astUtils = require("./utils/ast-utils");
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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 | /** @type {import('../shared/types').Rule} */
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19 | module.exports = {
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20 | meta: {
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21 | type: "suggestion",
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22 |
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23 | docs: {
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24 | description: "Disallow the use of `console`",
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25 | recommended: false,
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26 | url: "https://eslint.org/docs/latest/rules/no-console"
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27 | },
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28 |
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29 | schema: [
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30 | {
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31 | type: "object",
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32 | properties: {
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33 | allow: {
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34 | type: "array",
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35 | items: {
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36 | type: "string"
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37 | },
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38 | minItems: 1,
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39 | uniqueItems: true
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40 | }
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41 | },
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42 | additionalProperties: false
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43 | }
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44 | ],
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45 |
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46 | hasSuggestions: true,
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47 |
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48 | messages: {
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49 | unexpected: "Unexpected console statement.",
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50 | removeConsole: "Remove the console.{{ propertyName }}()."
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51 | }
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52 | },
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53 |
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54 | create(context) {
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55 | const options = context.options[0] || {};
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56 | const allowed = options.allow || [];
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57 | const sourceCode = context.sourceCode;
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58 |
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59 | /**
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60 | * Checks whether the given reference is 'console' or not.
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61 | * @param {eslint-scope.Reference} reference The reference to check.
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62 | * @returns {boolean} `true` if the reference is 'console'.
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63 | */
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64 | function isConsole(reference) {
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65 | const id = reference.identifier;
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66 |
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67 | return id && id.name === "console";
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68 | }
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69 |
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70 | /**
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71 | * Checks whether the property name of the given MemberExpression node
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72 | * is allowed by options or not.
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73 | * @param {ASTNode} node The MemberExpression node to check.
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74 | * @returns {boolean} `true` if the property name of the node is allowed.
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75 | */
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76 | function isAllowed(node) {
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77 | const propertyName = astUtils.getStaticPropertyName(node);
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78 |
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79 | return propertyName && allowed.includes(propertyName);
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80 | }
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81 |
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82 | /**
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83 | * Checks whether the given reference is a member access which is not
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84 | * allowed by options or not.
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85 | * @param {eslint-scope.Reference} reference The reference to check.
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86 | * @returns {boolean} `true` if the reference is a member access which
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87 | * is not allowed by options.
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88 | */
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89 | function isMemberAccessExceptAllowed(reference) {
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90 | const node = reference.identifier;
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91 | const parent = node.parent;
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92 |
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93 | return (
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94 | parent.type === "MemberExpression" &&
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95 | parent.object === node &&
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96 | !isAllowed(parent)
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97 | );
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98 | }
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99 |
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100 | /**
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101 | * Checks if removing the ExpressionStatement node will cause ASI to
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102 | * break.
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103 | * eg.
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104 | * foo()
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105 | * console.log();
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106 | * [1, 2, 3].forEach(a => doSomething(a))
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107 | *
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108 | * Removing the console.log(); statement should leave two statements, but
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109 | * here the two statements will become one because [ causes continuation after
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110 | * foo().
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111 | * @param {ASTNode} node The ExpressionStatement node to check.
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112 | * @returns {boolean} `true` if ASI will break after removing the ExpressionStatement
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113 | * node.
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114 | */
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115 | function maybeAsiHazard(node) {
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116 | const SAFE_TOKENS_BEFORE = /^[:;{]$/u; // One of :;{
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117 | const UNSAFE_CHARS_AFTER = /^[-[(/+`]/u; // One of [(/+-`
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118 |
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119 | const tokenBefore = sourceCode.getTokenBefore(node);
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120 | const tokenAfter = sourceCode.getTokenAfter(node);
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121 |
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122 | return (
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123 | Boolean(tokenAfter) &&
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124 | UNSAFE_CHARS_AFTER.test(tokenAfter.value) &&
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125 | tokenAfter.value !== "++" &&
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126 | tokenAfter.value !== "--" &&
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127 | Boolean(tokenBefore) &&
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128 | !SAFE_TOKENS_BEFORE.test(tokenBefore.value)
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129 | );
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130 | }
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131 |
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132 | /**
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133 | * Checks if the MemberExpression node's parent.parent.parent is a
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134 | * Program, BlockStatement, StaticBlock, or SwitchCase node. This check
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135 | * is necessary to avoid providing a suggestion that might cause a syntax error.
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136 | *
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137 | * eg. if (a) console.log(b), removing console.log() here will lead to a
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138 | * syntax error.
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139 | * if (a) { console.log(b) }, removing console.log() here is acceptable.
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140 | *
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141 | * Additionally, it checks if the callee of the CallExpression node is
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142 | * the node itself.
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143 | *
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144 | * eg. foo(console.log), cannot provide a suggestion here.
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145 | * @param {ASTNode} node The MemberExpression node to check.
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146 | * @returns {boolean} `true` if a suggestion can be provided for a node.
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147 | */
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148 | function canProvideSuggestions(node) {
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149 | return (
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150 | node.parent.type === "CallExpression" &&
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151 | node.parent.callee === node &&
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152 | node.parent.parent.type === "ExpressionStatement" &&
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153 | astUtils.STATEMENT_LIST_PARENTS.has(node.parent.parent.parent.type) &&
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154 | !maybeAsiHazard(node.parent.parent)
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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 | * Reports the given reference as a violation.
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160 | * @param {eslint-scope.Reference} reference The reference to report.
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161 | * @returns {void}
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162 | */
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163 | function report(reference) {
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164 | const node = reference.identifier.parent;
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165 |
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166 | const propertyName = astUtils.getStaticPropertyName(node);
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167 |
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168 | context.report({
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169 | node,
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170 | loc: node.loc,
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171 | messageId: "unexpected",
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172 | suggest: canProvideSuggestions(node)
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173 | ? [{
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174 | messageId: "removeConsole",
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175 | data: { propertyName },
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176 | fix(fixer) {
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177 | return fixer.remove(node.parent.parent);
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178 | }
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179 | }]
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180 | : []
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181 | });
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182 | }
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183 |
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184 | return {
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185 | "Program:exit"(node) {
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186 | const scope = sourceCode.getScope(node);
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187 | const consoleVar = astUtils.getVariableByName(scope, "console");
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188 | const shadowed = consoleVar && consoleVar.defs.length > 0;
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189 |
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190 | /*
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191 | * 'scope.through' includes all references to undefined
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192 | * variables. If the variable 'console' is not defined, it uses
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193 | * 'scope.through'.
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194 | */
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195 | const references = consoleVar
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196 | ? consoleVar.references
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197 | : scope.through.filter(isConsole);
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198 |
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199 | if (!shadowed) {
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200 | references
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201 | .filter(isMemberAccessExceptAllowed)
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202 | .forEach(report);
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203 | }
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204 | }
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205 | };
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206 | }
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207 | };
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