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node_modules/eslint/lib/rules/no-undef.js 2.12 KB
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  /**
   * @fileoverview Rule to flag references to undeclared variables.
   * @author Mark Macdonald
   */
  "use strict";
  
  //------------------------------------------------------------------------------
  // Helpers
  //------------------------------------------------------------------------------
  
  /**
   * Checks if the given node is the argument of a typeof operator.
   * @param {ASTNode} node The AST node being checked.
   * @returns {boolean} Whether or not the node is the argument of a typeof operator.
   */
  function hasTypeOfOperator(node) {
      const parent = node.parent;
  
      return parent.type === "UnaryExpression" && parent.operator === "typeof";
  }
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow the use of undeclared variables unless mentioned in `/*global */` comments",
              category: "Variables",
              recommended: true,
              url: "https://eslint.org/docs/rules/no-undef"
          },
  
          schema: [
              {
                  type: "object",
                  properties: {
                      typeof: {
                          type: "boolean"
                      }
                  },
                  additionalProperties: false
              }
          ]
      },
  
      create(context) {
          const options = context.options[0];
          const considerTypeOf = options && options.typeof === true || false;
  
          return {
              "Program:exit"(/* node */) {
                  const globalScope = context.getScope();
  
                  globalScope.through.forEach(ref => {
                      const identifier = ref.identifier;
  
                      if (!considerTypeOf && hasTypeOfOperator(identifier)) {
                          return;
                      }
  
                      context.report({
                          node: identifier,
                          message: "'{{name}}' is not defined.",
                          data: identifier
                      });
                  });
              }
          };
      }
  };