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node_modules/eslint/lib/rules/no-eq-null.js 1.18 KB
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  /**
   * @fileoverview Rule to flag comparisons to null without a type-checking
   * operator.
   * @author Ian Christian Myers
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow `null` comparisons without type-checking operators",
              category: "Best Practices",
              recommended: false,
              url: "https://eslint.org/docs/rules/no-eq-null"
          },
  
          schema: [],
  
          messages: {
              unexpected: "Use '===' to compare with null."
          }
      },
  
      create(context) {
  
          return {
  
              BinaryExpression(node) {
                  const badOperator = node.operator === "==" || node.operator === "!=";
  
                  if (node.right.type === "Literal" && node.right.raw === "null" && badOperator ||
                          node.left.type === "Literal" && node.left.raw === "null" && badOperator) {
                      context.report({ node, messageId: "unexpected" });
                  }
              }
          };
  
      }
  };