From fecc14506a7167dcb796887f61c9d5e412e2146c Mon Sep 17 00:00:00 2001
From: Sebastian Cao <cycsmail@gmail.com>
Date: Thu, 9 Jul 2026 13:33:44 +0800
Subject: [PATCH] Fixed `SyntaxError` when obfuscating a class that extends a
 boolean literal (#1420)

---
 CHANGELOG.md                                   |  4 ++++
 .../BooleanLiteralTransformer.ts               |  9 +++++++++
 .../BooleanLiteralTransformer.spec.ts          | 18 ++++++++++++++++++
 .../fixtures/super-class-value.js              |  1 +
 4 files changed, 32 insertions(+)
 create mode 100644 test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/fixtures/super-class-value.js

diff --git a/CHANGELOG.md b/CHANGELOG.md
index eb4ce789..f4ae6370 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 Change Log
 
+v5.4.5
+---
+* Fixed `SyntaxError` when obfuscating a class that extends a boolean literal (e.g. `class C extends true {}`). Fixes https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1131
+
 v5.4.4
 ---
 * Fixed `Invalid regular expression` error when obfuscating code that uses ES2025 RegExp pattern modifiers (e.g. `/(?i:abc)/`). Fixes https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1410
diff --git a/src/node-transformers/converting-transformers/BooleanLiteralTransformer.ts b/src/node-transformers/converting-transformers/BooleanLiteralTransformer.ts
index d3a6672c..cb8bbe16 100644
--- a/src/node-transformers/converting-transformers/BooleanLiteralTransformer.ts
+++ b/src/node-transformers/converting-transformers/BooleanLiteralTransformer.ts
@@ -66,6 +66,15 @@ export class BooleanLiteralTransformer extends AbstractNodeTransformer {
             return literalNode;
         }
 
+        /**
+         * A class heritage (`extends`) must be a `LeftHandSideExpression`, so replacing a
+         * boolean literal there with a unary expression (`class Foo extends ![] {}`) would
+         * produce a `SyntaxError`. Keep the original literal in that position.
+         */
+        if ('superClass' in parentNode && parentNode.superClass === literalNode) {
+            return literalNode;
+        }
+
         const literalValue: ESTree.SimpleLiteral['value'] = literalNode.value;
 
         const unaryExpressionNode: ESTree.UnaryExpression = literalValue
diff --git a/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/BooleanLiteralTransformer.spec.ts b/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/BooleanLiteralTransformer.spec.ts
index de8f025b..863ab61a 100644
--- a/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/BooleanLiteralTransformer.spec.ts
+++ b/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/BooleanLiteralTransformer.spec.ts
@@ -46,4 +46,22 @@ describe('BooleanLiteralTransformer', () => {
             assert.match(obfuscatedCode, regExp);
         });
     });
+
+    describe('boolean literal as a class super class', () => {
+        const regExp: RegExp = /^class Foo extends true *{}$/;
+
+        let obfuscatedCode: string;
+
+        before(() => {
+            const code: string = readFileAsString(__dirname + '/fixtures/super-class-value.js');
+
+            obfuscatedCode = JavaScriptObfuscator.obfuscate(code, {
+                ...NO_ADDITIONAL_NODES_PRESET
+            }).getObfuscatedCode();
+        });
+
+        it('should not transform a boolean literal used as a class heritage to avoid a `SyntaxError`', () => {
+            assert.match(obfuscatedCode, regExp);
+        });
+    });
 });
diff --git a/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/fixtures/super-class-value.js b/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/fixtures/super-class-value.js
new file mode 100644
index 00000000..7e5c9c82
--- /dev/null
+++ b/test/functional-tests/node-transformers/converting-transformers/boolean-literal-transformer/fixtures/super-class-value.js
@@ -0,0 +1 @@
+class Foo extends true {}