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node_modules/eslint/lib/rules/no-eq-null.js

@@ -0,0 +1,46 @@
+/**
+ * @fileoverview Rule to flag comparisons to null without a type-checking
+ * operator.
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        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" });
+                }
+            }
+        };
+
+    }
+};