[jsinterp] Fix div bug breaking player 8c7583ff

Thx bashonly: https://github.com/ytdl-org/youtube-dl/issues/32292#issuecomment-1585639223
Fixes #32292

test/test_jsinterp.py

@@ -33,6 +33,55 @@ class TestJSInterpreter(unittest.TestCase):
         jsi = JSInterpreter('function x4(a){return 2*a+1;}')
         self.assertEqual(jsi.call_function('x4', 3), 7)
 
+    def test_add(self):
+        jsi = JSInterpreter('function f(){return 42 + 7;}')
+        self.assertEqual(jsi.call_function('f'), 49)
+        jsi = JSInterpreter('function f(){return 42 + undefined;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+        jsi = JSInterpreter('function f(){return 42 + null;}')
+        self.assertEqual(jsi.call_function('f'), 42)
+
+    def test_sub(self):
+        jsi = JSInterpreter('function f(){return 42 - 7;}')
+        self.assertEqual(jsi.call_function('f'), 35)
+        jsi = JSInterpreter('function f(){return 42 - undefined;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+        jsi = JSInterpreter('function f(){return 42 - null;}')
+        self.assertEqual(jsi.call_function('f'), 42)
+
+    def test_mul(self):
+        jsi = JSInterpreter('function f(){return 42 * 7;}')
+        self.assertEqual(jsi.call_function('f'), 294)
+        jsi = JSInterpreter('function f(){return 42 * undefined;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+        jsi = JSInterpreter('function f(){return 42 * null;}')
+        self.assertEqual(jsi.call_function('f'), 0)
+
+    def test_div(self):
+        jsi = JSInterpreter('function f(a, b){return a / b;}')
+        self.assertTrue(math.isnan(jsi.call_function('f', 0, 0)))
+        self.assertTrue(math.isnan(jsi.call_function('f', JS_Undefined, 1)))
+        self.assertTrue(math.isinf(jsi.call_function('f', 2, 0)))
+        self.assertEqual(jsi.call_function('f', 0, 3), 0)
+
+    def test_mod(self):
+        jsi = JSInterpreter('function f(){return 42 % 7;}')
+        self.assertEqual(jsi.call_function('f'), 0)
+        jsi = JSInterpreter('function f(){return 42 % 0;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+        jsi = JSInterpreter('function f(){return 42 % undefined;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+
+    def test_exp(self):
+        jsi = JSInterpreter('function f(){return 42 ** 2;}')
+        self.assertEqual(jsi.call_function('f'), 1764)
+        jsi = JSInterpreter('function f(){return 42 ** undefined;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+        jsi = JSInterpreter('function f(){return 42 ** null;}')
+        self.assertEqual(jsi.call_function('f'), 1)
+        jsi = JSInterpreter('function f(){return undefined ** 42;}')
+        self.assertTrue(math.isnan(jsi.call_function('f')))
+
     def test_empty_return(self):
         jsi = JSInterpreter('function f(){return; y()}')
         self.assertEqual(jsi.call_function('f'), None)

test/test_youtube_signature.py

@@ -151,6 +151,10 @@ _NSIG_TESTS = [
         'https://www.youtube.com/s/player/cfa9e7cb/player_ias.vflset/en_US/base.js',
         'qO0NiMtYQ7TeJnfFG2', 'k9cuJDHNS5O7kQ',
     ),
+    (
+        'https://www.youtube.com/s/player/8c7583ff/player_ias.vflset/en_US/base.js',
+        'E2AQVN6y_zM7uN9w8z', '9A2dbY5GDZrt9A',
+    ),
 ]
 
 

youtube_dl/jsinterp.py

@@ -82,7 +82,7 @@ def _js_arith_op(op):
 
 
 def _js_div(a, b):
-    if JS_Undefined in (a, b) or not (a and b):
+    if JS_Undefined in (a, b) or not (a or b):
         return _NaN
     return operator.truediv(a or 0, b) if b else float('inf')