[jsinterp] Improve nested attribute support

test/test_jsinterp.py

@@ -403,6 +403,8 @@ class TestJSInterpreter(unittest.TestCase):
         test_result = list('test')
         tests = [
             'function f(a, b){return a.split(b)}',
+            'function f(a, b){return a["split"](b)}',
+            'function f(a, b){let x = ["split"]; return a[x[0]](b)}',
             'function f(a, b){return String.prototype.split.call(a, b)}',
             'function f(a, b){return String.prototype.split.apply(a, [b])}',
         ]

yt_dlp/jsinterp.py

@@ -614,7 +614,7 @@ class JSInterpreter:
             )|(?P<indexing>
                 (?P<in>{_NAME_RE})\[(?P<idx>.+)\]$
             )|(?P<attribute>
-                (?P<var>{_NAME_RE})(?:(?P<nullish>\?)?\.(?P<member>[^(]+)|\[(?P<member2>[^\]]+)\])\s*
+                (?P<var>{_NAME_RE})(?:(?P<nullish>\?)?\.(?P<member>[^(]+)|\[(?P<member2>[^\[\]]+(?:\[[^\[\]]+(?:\[[^\]]+\])?\])?)\])\s*
             )|(?P<function>
                 (?P<fname>{_NAME_RE})\((?P<args>.*)\)$
             )''', expr)