.

qwen/nodejs/node_modules/eslint/lib/rules/no-negated-condition.js

@@ -0,0 +1,95 @@
+/**
+ * @fileoverview Rule to disallow a negated condition
+ * @author Alberto Rodríguez
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Disallow negated conditions",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/rules/no-negated-condition"
+        },
+
+        schema: [],
+
+        messages: {
+            unexpectedNegated: "Unexpected negated condition."
+        }
+    },
+
+    create(context) {
+
+        /**
+         * Determines if a given node is an if-else without a condition on the else
+         * @param {ASTNode} node The node to check.
+         * @returns {boolean} True if the node has an else without an if.
+         * @private
+         */
+        function hasElseWithoutCondition(node) {
+            return node.alternate && node.alternate.type !== "IfStatement";
+        }
+
+        /**
+         * Determines if a given node is a negated unary expression
+         * @param {Object} test The test object to check.
+         * @returns {boolean} True if the node is a negated unary expression.
+         * @private
+         */
+        function isNegatedUnaryExpression(test) {
+            return test.type === "UnaryExpression" && test.operator === "!";
+        }
+
+        /**
+         * Determines if a given node is a negated binary expression
+         * @param {Test} test The test to check.
+         * @returns {boolean} True if the node is a negated binary expression.
+         * @private
+         */
+        function isNegatedBinaryExpression(test) {
+            return test.type === "BinaryExpression" &&
+                (test.operator === "!=" || test.operator === "!==");
+        }
+
+        /**
+         * Determines if a given node has a negated if expression
+         * @param {ASTNode} node The node to check.
+         * @returns {boolean} True if the node has a negated if expression.
+         * @private
+         */
+        function isNegatedIf(node) {
+            return isNegatedUnaryExpression(node.test) || isNegatedBinaryExpression(node.test);
+        }
+
+        return {
+            IfStatement(node) {
+                if (!hasElseWithoutCondition(node)) {
+                    return;
+                }
+
+                if (isNegatedIf(node)) {
+                    context.report({
+                        node,
+                        messageId: "unexpectedNegated"
+                    });
+                }
+            },
+            ConditionalExpression(node) {
+                if (isNegatedIf(node)) {
+                    context.report({
+                        node,
+                        messageId: "unexpectedNegated"
+                    });
+                }
+            }
+        };
+    }
+};