Adding upstream version 2024.03.10.upstream/2024.03.10

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 853 insertions, 0 deletions

diff --git a/yt_dlp/jsinterp.py b/yt_dlp/jsinterp.py
new file mode 100644
index 0000000..bda3fb4
--- /dev/null
+++ b/yt_dlp/jsinterp.py
@@ -0,0 +1,853 @@
+import collections
+import contextlib
+import itertools
+import json
+import math
+import operator
+import re
+
+from .utils import (
+    NO_DEFAULT,
+    ExtractorError,
+    function_with_repr,
+    js_to_json,
+    remove_quotes,
+    truncate_string,
+    unified_timestamp,
+    write_string,
+)
+
+
+def _js_bit_op(op):
+    def zeroise(x):
+        if x in (None, JS_Undefined):
+            return 0
+        with contextlib.suppress(TypeError):
+            if math.isnan(x):  # NB: NaN cannot be checked by membership
+                return 0
+        return x
+
+    def wrapped(a, b):
+        return op(zeroise(a), zeroise(b)) & 0xffffffff
+
+    return wrapped
+
+
+def _js_arith_op(op):
+
+    def wrapped(a, b):
+        if JS_Undefined in (a, b):
+            return float('nan')
+        return op(a or 0, b or 0)
+
+    return wrapped
+
+
+def _js_div(a, b):
+    if JS_Undefined in (a, b) or not (a or b):
+        return float('nan')
+    return (a or 0) / b if b else float('inf')
+
+
+def _js_mod(a, b):
+    if JS_Undefined in (a, b) or not b:
+        return float('nan')
+    return (a or 0) % b
+
+
+def _js_exp(a, b):
+    if not b:
+        return 1  # even 0 ** 0 !!
+    elif JS_Undefined in (a, b):
+        return float('nan')
+    return (a or 0) ** b
+
+
+def _js_eq_op(op):
+
+    def wrapped(a, b):
+        if {a, b} <= {None, JS_Undefined}:
+            return op(a, a)
+        return op(a, b)
+
+    return wrapped
+
+
+def _js_comp_op(op):
+
+    def wrapped(a, b):
+        if JS_Undefined in (a, b):
+            return False
+        if isinstance(a, str) or isinstance(b, str):
+            return op(str(a or 0), str(b or 0))
+        return op(a or 0, b or 0)
+
+    return wrapped
+
+
+def _js_ternary(cndn, if_true=True, if_false=False):
+    """Simulate JS's ternary operator (cndn?if_true:if_false)"""
+    if cndn in (False, None, 0, '', JS_Undefined):
+        return if_false
+    with contextlib.suppress(TypeError):
+        if math.isnan(cndn):  # NB: NaN cannot be checked by membership
+            return if_false
+    return if_true
+
+
+# Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
+_OPERATORS = {  # None => Defined in JSInterpreter._operator
+    '?': None,
+    '??': None,
+    '||': None,
+    '&&': None,
+
+    '|': _js_bit_op(operator.or_),
+    '^': _js_bit_op(operator.xor),
+    '&': _js_bit_op(operator.and_),
+
+    '===': operator.is_,
+    '!==': operator.is_not,
+    '==': _js_eq_op(operator.eq),
+    '!=': _js_eq_op(operator.ne),
+
+    '<=': _js_comp_op(operator.le),
+    '>=': _js_comp_op(operator.ge),
+    '<': _js_comp_op(operator.lt),
+    '>': _js_comp_op(operator.gt),
+
+    '>>': _js_bit_op(operator.rshift),
+    '<<': _js_bit_op(operator.lshift),
+
+    '+': _js_arith_op(operator.add),
+    '-': _js_arith_op(operator.sub),
+
+    '*': _js_arith_op(operator.mul),
+    '%': _js_mod,
+    '/': _js_div,
+    '**': _js_exp,
+}
+
+_COMP_OPERATORS = {'===', '!==', '==', '!=', '<=', '>=', '<', '>'}
+
+_NAME_RE = r'[a-zA-Z_$][\w$]*'
+_MATCHING_PARENS = dict(zip(*zip('()', '{}', '[]')))
+_QUOTES = '\'"/'
+
+
+class JS_Undefined:
+    pass
+
+
+class JS_Break(ExtractorError):
+    def __init__(self):
+        ExtractorError.__init__(self, 'Invalid break')
+
+
+class JS_Continue(ExtractorError):
+    def __init__(self):
+        ExtractorError.__init__(self, 'Invalid continue')
+
+
+class JS_Throw(ExtractorError):
+    def __init__(self, e):
+        self.error = e
+        ExtractorError.__init__(self, f'Uncaught exception {e}')
+
+
+class LocalNameSpace(collections.ChainMap):
+    def __setitem__(self, key, value):
+        for scope in self.maps:
+            if key in scope:
+                scope[key] = value
+                return
+        self.maps[0][key] = value
+
+    def __delitem__(self, key):
+        raise NotImplementedError('Deleting is not supported')
+
+
+class Debugger:
+    import sys
+    ENABLED = False and 'pytest' in sys.modules
+
+    @staticmethod
+    def write(*args, level=100):
+        write_string(f'[debug] JS: {"  " * (100 - level)}'
+                     f'{" ".join(truncate_string(str(x), 50, 50) for x in args)}\n')
+
+    @classmethod
+    def wrap_interpreter(cls, f):
+        def interpret_statement(self, stmt, local_vars, allow_recursion, *args, **kwargs):
+            if cls.ENABLED and stmt.strip():
+                cls.write(stmt, level=allow_recursion)
+            try:
+                ret, should_ret = f(self, stmt, local_vars, allow_recursion, *args, **kwargs)
+            except Exception as e:
+                if cls.ENABLED:
+                    if isinstance(e, ExtractorError):
+                        e = e.orig_msg
+                    cls.write('=> Raises:', e, '<-|', stmt, level=allow_recursion)
+                raise
+            if cls.ENABLED and stmt.strip():
+                if should_ret or not repr(ret) == stmt:
+                    cls.write(['->', '=>'][should_ret], repr(ret), '<-|', stmt, level=allow_recursion)
+            return ret, should_ret
+        return interpret_statement
+
+
+class JSInterpreter:
+    __named_object_counter = 0
+
+    _RE_FLAGS = {
+        # special knowledge: Python's re flags are bitmask values, current max 128
+        # invent new bitmask values well above that for literal parsing
+        # TODO: new pattern class to execute matches with these flags
+        'd': 1024,  # Generate indices for substring matches
+        'g': 2048,  # Global search
+        'i': re.I,  # Case-insensitive search
+        'm': re.M,  # Multi-line search
+        's': re.S,  # Allows . to match newline characters
+        'u': re.U,  # Treat a pattern as a sequence of unicode code points
+        'y': 4096,  # Perform a "sticky" search that matches starting at the current position in the target string
+    }
+
+    def __init__(self, code, objects=None):
+        self.code, self._functions = code, {}
+        self._objects = {} if objects is None else objects
+
+    class Exception(ExtractorError):
+        def __init__(self, msg, expr=None, *args, **kwargs):
+            if expr is not None:
+                msg = f'{msg.rstrip()} in: {truncate_string(expr, 50, 50)}'
+            super().__init__(msg, *args, **kwargs)
+
+    def _named_object(self, namespace, obj):
+        self.__named_object_counter += 1
+        name = f'__yt_dlp_jsinterp_obj{self.__named_object_counter}'
+        if callable(obj) and not isinstance(obj, function_with_repr):
+            obj = function_with_repr(obj, f'F<{self.__named_object_counter}>')
+        namespace[name] = obj
+        return name
+
+    @classmethod
+    def _regex_flags(cls, expr):
+        flags = 0
+        if not expr:
+            return flags, expr
+        for idx, ch in enumerate(expr):
+            if ch not in cls._RE_FLAGS:
+                break
+            flags |= cls._RE_FLAGS[ch]
+        return flags, expr[idx + 1:]
+
+    @staticmethod
+    def _separate(expr, delim=',', max_split=None):
+        OP_CHARS = '+-*/%&|^=<>!,;{}:['
+        if not expr:
+            return
+        counters = {k: 0 for k in _MATCHING_PARENS.values()}
+        start, splits, pos, delim_len = 0, 0, 0, len(delim) - 1
+        in_quote, escaping, after_op, in_regex_char_group = None, False, True, False
+        for idx, char in enumerate(expr):
+            if not in_quote and char in _MATCHING_PARENS:
+                counters[_MATCHING_PARENS[char]] += 1
+            elif not in_quote and char in counters:
+                # Something's wrong if we get negative, but ignore it anyway
+                if counters[char]:
+                    counters[char] -= 1
+            elif not escaping:
+                if char in _QUOTES and in_quote in (char, None):
+                    if in_quote or after_op or char != '/':
+                        in_quote = None if in_quote and not in_regex_char_group else char
+                elif in_quote == '/' and char in '[]':
+                    in_regex_char_group = char == '['
+            escaping = not escaping and in_quote and char == '\\'
+            in_unary_op = (not in_quote and not in_regex_char_group
+                           and after_op not in (True, False) and char in '-+')
+            after_op = char if (not in_quote and char in OP_CHARS) else (char.isspace() and after_op)
+
+            if char != delim[pos] or any(counters.values()) or in_quote or in_unary_op:
+                pos = 0
+                continue
+            elif pos != delim_len:
+                pos += 1
+                continue
+            yield expr[start: idx - delim_len]
+            start, pos = idx + 1, 0
+            splits += 1
+            if max_split and splits >= max_split:
+                break
+        yield expr[start:]
+
+    @classmethod
+    def _separate_at_paren(cls, expr, delim=None):
+        if delim is None:
+            delim = expr and _MATCHING_PARENS[expr[0]]
+        separated = list(cls._separate(expr, delim, 1))
+        if len(separated) < 2:
+            raise cls.Exception(f'No terminating paren {delim}', expr)
+        return separated[0][1:].strip(), separated[1].strip()
+
+    def _operator(self, op, left_val, right_expr, expr, local_vars, allow_recursion):
+        if op in ('||', '&&'):
+            if (op == '&&') ^ _js_ternary(left_val):
+                return left_val  # short circuiting
+        elif op == '??':
+            if left_val not in (None, JS_Undefined):
+                return left_val
+        elif op == '?':
+            right_expr = _js_ternary(left_val, *self._separate(right_expr, ':', 1))
+
+        right_val = self.interpret_expression(right_expr, local_vars, allow_recursion)
+        if not _OPERATORS.get(op):
+            return right_val
+
+        try:
+            return _OPERATORS[op](left_val, right_val)
+        except Exception as e:
+            raise self.Exception(f'Failed to evaluate {left_val!r} {op} {right_val!r}', expr, cause=e)
+
+    def _index(self, obj, idx, allow_undefined=False):
+        if idx == 'length':
+            return len(obj)
+        try:
+            return obj[int(idx)] if isinstance(obj, list) else obj[idx]
+        except Exception as e:
+            if allow_undefined:
+                return JS_Undefined
+            raise self.Exception(f'Cannot get index {idx}', repr(obj), cause=e)
+
+    def _dump(self, obj, namespace):
+        try:
+            return json.dumps(obj)
+        except TypeError:
+            return self._named_object(namespace, obj)
+
+    @Debugger.wrap_interpreter
+    def interpret_statement(self, stmt, local_vars, allow_recursion=100):
+        if allow_recursion < 0:
+            raise self.Exception('Recursion limit reached')
+        allow_recursion -= 1
+
+        should_return = False
+        sub_statements = list(self._separate(stmt, ';')) or ['']
+        expr = stmt = sub_statements.pop().strip()
+
+        for sub_stmt in sub_statements:
+            ret, should_return = self.interpret_statement(sub_stmt, local_vars, allow_recursion)
+            if should_return:
+                return ret, should_return
+
+        m = re.match(r'(?P<var>(?:var|const|let)\s)|return(?:\s+|(?=["\'])|$)|(?P<throw>throw\s+)', stmt)
+        if m:
+            expr = stmt[len(m.group(0)):].strip()
+            if m.group('throw'):
+                raise JS_Throw(self.interpret_expression(expr, local_vars, allow_recursion))
+            should_return = not m.group('var')
+        if not expr:
+            return None, should_return
+
+        if expr[0] in _QUOTES:
+            inner, outer = self._separate(expr, expr[0], 1)
+            if expr[0] == '/':
+                flags, outer = self._regex_flags(outer)
+                # We don't support regex methods yet, so no point compiling it
+                inner = f'{inner}/{flags}'
+                # Avoid https://github.com/python/cpython/issues/74534
+                # inner = re.compile(inner[1:].replace('[[', r'[\['), flags=flags)
+            else:
+                inner = json.loads(js_to_json(f'{inner}{expr[0]}', strict=True))
+            if not outer:
+                return inner, should_return
+            expr = self._named_object(local_vars, inner) + outer
+
+        if expr.startswith('new '):
+            obj = expr[4:]
+            if obj.startswith('Date('):
+                left, right = self._separate_at_paren(obj[4:])
+                date = unified_timestamp(
+                    self.interpret_expression(left, local_vars, allow_recursion), False)
+                if date is None:
+                    raise self.Exception(f'Failed to parse date {left!r}', expr)
+                expr = self._dump(int(date * 1000), local_vars) + right
+            else:
+                raise self.Exception(f'Unsupported object {obj}', expr)
+
+        if expr.startswith('void '):
+            left = self.interpret_expression(expr[5:], local_vars, allow_recursion)
+            return None, should_return
+
+        if expr.startswith('{'):
+            inner, outer = self._separate_at_paren(expr)
+            # try for object expression (Map)
+            sub_expressions = [list(self._separate(sub_expr.strip(), ':', 1)) for sub_expr in self._separate(inner)]
+            if all(len(sub_expr) == 2 for sub_expr in sub_expressions):
+                def dict_item(key, val):
+                    val = self.interpret_expression(val, local_vars, allow_recursion)
+                    if re.match(_NAME_RE, key):
+                        return key, val
+                    return self.interpret_expression(key, local_vars, allow_recursion), val
+
+                return dict(dict_item(k, v) for k, v in sub_expressions), should_return
+
+            inner, should_abort = self.interpret_statement(inner, local_vars, allow_recursion)
+            if not outer or should_abort:
+                return inner, should_abort or should_return
+            else:
+                expr = self._dump(inner, local_vars) + outer
+
+        if expr.startswith('('):
+            inner, outer = self._separate_at_paren(expr)
+            inner, should_abort = self.interpret_statement(inner, local_vars, allow_recursion)
+            if not outer or should_abort:
+                return inner, should_abort or should_return
+            else:
+                expr = self._dump(inner, local_vars) + outer
+
+        if expr.startswith('['):
+            inner, outer = self._separate_at_paren(expr)
+            name = self._named_object(local_vars, [
+                self.interpret_expression(item, local_vars, allow_recursion)
+                for item in self._separate(inner)])
+            expr = name + outer
+
+        m = re.match(r'''(?x)
+                (?P<try>try)\s*\{|
+                (?P<if>if)\s*\(|
+                (?P<switch>switch)\s*\(|
+                (?P<for>for)\s*\(
+                ''', expr)
+        md = m.groupdict() if m else {}
+        if md.get('if'):
+            cndn, expr = self._separate_at_paren(expr[m.end() - 1:])
+            if_expr, expr = self._separate_at_paren(expr.lstrip())
+            # TODO: "else if" is not handled
+            else_expr = None
+            m = re.match(r'else\s*{', expr)
+            if m:
+                else_expr, expr = self._separate_at_paren(expr[m.end() - 1:])
+            cndn = _js_ternary(self.interpret_expression(cndn, local_vars, allow_recursion))
+            ret, should_abort = self.interpret_statement(
+                if_expr if cndn else else_expr, local_vars, allow_recursion)
+            if should_abort:
+                return ret, True
+
+        if md.get('try'):
+            try_expr, expr = self._separate_at_paren(expr[m.end() - 1:])
+            err = None
+            try:
+                ret, should_abort = self.interpret_statement(try_expr, local_vars, allow_recursion)
+                if should_abort:
+                    return ret, True
+            except Exception as e:
+                # XXX: This works for now, but makes debugging future issues very hard
+                err = e
+
+            pending = (None, False)
+            m = re.match(fr'catch\s*(?P<err>\(\s*{_NAME_RE}\s*\))?\{{', expr)
+            if m:
+                sub_expr, expr = self._separate_at_paren(expr[m.end() - 1:])
+                if err:
+                    catch_vars = {}
+                    if m.group('err'):
+                        catch_vars[m.group('err')] = err.error if isinstance(err, JS_Throw) else err
+                    catch_vars = local_vars.new_child(catch_vars)
+                    err, pending = None, self.interpret_statement(sub_expr, catch_vars, allow_recursion)
+
+            m = re.match(r'finally\s*\{', expr)
+            if m:
+                sub_expr, expr = self._separate_at_paren(expr[m.end() - 1:])
+                ret, should_abort = self.interpret_statement(sub_expr, local_vars, allow_recursion)
+                if should_abort:
+                    return ret, True
+
+            ret, should_abort = pending
+            if should_abort:
+                return ret, True
+
+            if err:
+                raise err
+
+        elif md.get('for'):
+            constructor, remaining = self._separate_at_paren(expr[m.end() - 1:])
+            if remaining.startswith('{'):
+                body, expr = self._separate_at_paren(remaining)
+            else:
+                switch_m = re.match(r'switch\s*\(', remaining)  # FIXME
+                if switch_m:
+                    switch_val, remaining = self._separate_at_paren(remaining[switch_m.end() - 1:])
+                    body, expr = self._separate_at_paren(remaining, '}')
+                    body = 'switch(%s){%s}' % (switch_val, body)
+                else:
+                    body, expr = remaining, ''
+            start, cndn, increment = self._separate(constructor, ';')
+            self.interpret_expression(start, local_vars, allow_recursion)
+            while True:
+                if not _js_ternary(self.interpret_expression(cndn, local_vars, allow_recursion)):
+                    break
+                try:
+                    ret, should_abort = self.interpret_statement(body, local_vars, allow_recursion)
+                    if should_abort:
+                        return ret, True
+                except JS_Break:
+                    break
+                except JS_Continue:
+                    pass
+                self.interpret_expression(increment, local_vars, allow_recursion)
+
+        elif md.get('switch'):
+            switch_val, remaining = self._separate_at_paren(expr[m.end() - 1:])
+            switch_val = self.interpret_expression(switch_val, local_vars, allow_recursion)
+            body, expr = self._separate_at_paren(remaining, '}')
+            items = body.replace('default:', 'case default:').split('case ')[1:]
+            for default in (False, True):
+                matched = False
+                for item in items:
+                    case, stmt = (i.strip() for i in self._separate(item, ':', 1))
+                    if default:
+                        matched = matched or case == 'default'
+                    elif not matched:
+                        matched = (case != 'default'
+                                   and switch_val == self.interpret_expression(case, local_vars, allow_recursion))
+                    if not matched:
+                        continue
+                    try:
+                        ret, should_abort = self.interpret_statement(stmt, local_vars, allow_recursion)
+                        if should_abort:
+                            return ret
+                    except JS_Break:
+                        break
+                if matched:
+                    break
+
+        if md:
+            ret, should_abort = self.interpret_statement(expr, local_vars, allow_recursion)
+            return ret, should_abort or should_return
+
+        # Comma separated statements
+        sub_expressions = list(self._separate(expr))
+        if len(sub_expressions) > 1:
+            for sub_expr in sub_expressions:
+                ret, should_abort = self.interpret_statement(sub_expr, local_vars, allow_recursion)
+                if should_abort:
+                    return ret, True
+            return ret, False
+
+        for m in re.finditer(rf'''(?x)
+                (?P<pre_sign>\+\+|--)(?P<var1>{_NAME_RE})|
+                (?P<var2>{_NAME_RE})(?P<post_sign>\+\+|--)''', expr):
+            var = m.group('var1') or m.group('var2')
+            start, end = m.span()
+            sign = m.group('pre_sign') or m.group('post_sign')
+            ret = local_vars[var]
+            local_vars[var] += 1 if sign[0] == '+' else -1
+            if m.group('pre_sign'):
+                ret = local_vars[var]
+            expr = expr[:start] + self._dump(ret, local_vars) + expr[end:]
+
+        if not expr:
+            return None, should_return
+
+        m = re.match(fr'''(?x)
+            (?P<assign>
+                (?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?\s*
+                (?P<op>{"|".join(map(re.escape, set(_OPERATORS) - _COMP_OPERATORS))})?
+                =(?!=)(?P<expr>.*)$
+            )|(?P<return>
+                (?!if|return|true|false|null|undefined|NaN)(?P<name>{_NAME_RE})$
+            )|(?P<indexing>
+                (?P<in>{_NAME_RE})\[(?P<idx>.+)\]$
+            )|(?P<attribute>
+                (?P<var>{_NAME_RE})(?:(?P<nullish>\?)?\.(?P<member>[^(]+)|\[(?P<member2>[^\]]+)\])\s*
+            )|(?P<function>
+                (?P<fname>{_NAME_RE})\((?P<args>.*)\)$
+            )''', expr)
+        if m and m.group('assign'):
+            left_val = local_vars.get(m.group('out'))
+
+            if not m.group('index'):
+                local_vars[m.group('out')] = self._operator(
+                    m.group('op'), left_val, m.group('expr'), expr, local_vars, allow_recursion)
+                return local_vars[m.group('out')], should_return
+            elif left_val in (None, JS_Undefined):
+                raise self.Exception(f'Cannot index undefined variable {m.group("out")}', expr)
+
+            idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
+            if not isinstance(idx, (int, float)):
+                raise self.Exception(f'List index {idx} must be integer', expr)
+            idx = int(idx)
+            left_val[idx] = self._operator(
+                m.group('op'), self._index(left_val, idx), m.group('expr'), expr, local_vars, allow_recursion)
+            return left_val[idx], should_return
+
+        elif expr.isdigit():
+            return int(expr), should_return
+
+        elif expr == 'break':
+            raise JS_Break()
+        elif expr == 'continue':
+            raise JS_Continue()
+        elif expr == 'undefined':
+            return JS_Undefined, should_return
+        elif expr == 'NaN':
+            return float('NaN'), should_return
+
+        elif m and m.group('return'):
+            return local_vars.get(m.group('name'), JS_Undefined), should_return
+
+        with contextlib.suppress(ValueError):
+            return json.loads(js_to_json(expr, strict=True)), should_return
+
+        if m and m.group('indexing'):
+            val = local_vars[m.group('in')]
+            idx = self.interpret_expression(m.group('idx'), local_vars, allow_recursion)
+            return self._index(val, idx), should_return
+
+        for op in _OPERATORS:
+            separated = list(self._separate(expr, op))
+            right_expr = separated.pop()
+            while True:
+                if op in '?<>*-' and len(separated) > 1 and not separated[-1].strip():
+                    separated.pop()
+                elif not (separated and op == '?' and right_expr.startswith('.')):
+                    break
+                right_expr = f'{op}{right_expr}'
+                if op != '-':
+                    right_expr = f'{separated.pop()}{op}{right_expr}'
+            if not separated:
+                continue
+            left_val = self.interpret_expression(op.join(separated), local_vars, allow_recursion)
+            return self._operator(op, left_val, right_expr, expr, local_vars, allow_recursion), should_return
+
+        if m and m.group('attribute'):
+            variable, member, nullish = m.group('var', 'member', 'nullish')
+            if not member:
+                member = self.interpret_expression(m.group('member2'), local_vars, allow_recursion)
+            arg_str = expr[m.end():]
+            if arg_str.startswith('('):
+                arg_str, remaining = self._separate_at_paren(arg_str)
+            else:
+                arg_str, remaining = None, arg_str
+
+            def assertion(cndn, msg):
+                """ assert, but without risk of getting optimized out """
+                if not cndn:
+                    raise self.Exception(f'{member} {msg}', expr)
+
+            def eval_method():
+                if (variable, member) == ('console', 'debug'):
+                    if Debugger.ENABLED:
+                        Debugger.write(self.interpret_expression(f'[{arg_str}]', local_vars, allow_recursion))
+                    return
+
+                types = {
+                    'String': str,
+                    'Math': float,
+                }
+                obj = local_vars.get(variable, types.get(variable, NO_DEFAULT))
+                if obj is NO_DEFAULT:
+                    if variable not in self._objects:
+                        try:
+                            self._objects[variable] = self.extract_object(variable)
+                        except self.Exception:
+                            if not nullish:
+                                raise
+                    obj = self._objects.get(variable, JS_Undefined)
+
+                if nullish and obj is JS_Undefined:
+                    return JS_Undefined
+
+                # Member access
+                if arg_str is None:
+                    return self._index(obj, member, nullish)
+
+                # Function call
+                argvals = [
+                    self.interpret_expression(v, local_vars, allow_recursion)
+                    for v in self._separate(arg_str)]
+
+                if obj == str:
+                    if member == 'fromCharCode':
+                        assertion(argvals, 'takes one or more arguments')
+                        return ''.join(map(chr, argvals))
+                    raise self.Exception(f'Unsupported String method {member}', expr)
+                elif obj == float:
+                    if member == 'pow':
+                        assertion(len(argvals) == 2, 'takes two arguments')
+                        return argvals[0] ** argvals[1]
+                    raise self.Exception(f'Unsupported Math method {member}', expr)
+
+                if member == 'split':
+                    assertion(argvals, 'takes one or more arguments')
+                    assertion(len(argvals) == 1, 'with limit argument is not implemented')
+                    return obj.split(argvals[0]) if argvals[0] else list(obj)
+                elif member == 'join':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(len(argvals) == 1, 'takes exactly one argument')
+                    return argvals[0].join(obj)
+                elif member == 'reverse':
+                    assertion(not argvals, 'does not take any arguments')
+                    obj.reverse()
+                    return obj
+                elif member == 'slice':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(len(argvals) == 1, 'takes exactly one argument')
+                    return obj[argvals[0]:]
+                elif member == 'splice':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(argvals, 'takes one or more arguments')
+                    index, howMany = map(int, (argvals + [len(obj)])[:2])
+                    if index < 0:
+                        index += len(obj)
+                    add_items = argvals[2:]
+                    res = []
+                    for i in range(index, min(index + howMany, len(obj))):
+                        res.append(obj.pop(index))
+                    for i, item in enumerate(add_items):
+                        obj.insert(index + i, item)
+                    return res
+                elif member == 'unshift':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(argvals, 'takes one or more arguments')
+                    for item in reversed(argvals):
+                        obj.insert(0, item)
+                    return obj
+                elif member == 'pop':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(not argvals, 'does not take any arguments')
+                    if not obj:
+                        return
+                    return obj.pop()
+                elif member == 'push':
+                    assertion(argvals, 'takes one or more arguments')
+                    obj.extend(argvals)
+                    return obj
+                elif member == 'forEach':
+                    assertion(argvals, 'takes one or more arguments')
+                    assertion(len(argvals) <= 2, 'takes at-most 2 arguments')
+                    f, this = (argvals + [''])[:2]
+                    return [f((item, idx, obj), {'this': this}, allow_recursion) for idx, item in enumerate(obj)]
+                elif member == 'indexOf':
+                    assertion(argvals, 'takes one or more arguments')
+                    assertion(len(argvals) <= 2, 'takes at-most 2 arguments')
+                    idx, start = (argvals + [0])[:2]
+                    try:
+                        return obj.index(idx, start)
+                    except ValueError:
+                        return -1
+                elif member == 'charCodeAt':
+                    assertion(isinstance(obj, str), 'must be applied on a string')
+                    assertion(len(argvals) == 1, 'takes exactly one argument')
+                    idx = argvals[0] if isinstance(argvals[0], int) else 0
+                    if idx >= len(obj):
+                        return None
+                    return ord(obj[idx])
+
+                idx = int(member) if isinstance(obj, list) else member
+                return obj[idx](argvals, allow_recursion=allow_recursion)
+
+            if remaining:
+                ret, should_abort = self.interpret_statement(
+                    self._named_object(local_vars, eval_method()) + remaining,
+                    local_vars, allow_recursion)
+                return ret, should_return or should_abort
+            else:
+                return eval_method(), should_return
+
+        elif m and m.group('function'):
+            fname = m.group('fname')
+            argvals = [self.interpret_expression(v, local_vars, allow_recursion)
+                       for v in self._separate(m.group('args'))]
+            if fname in local_vars:
+                return local_vars[fname](argvals, allow_recursion=allow_recursion), should_return
+            elif fname not in self._functions:
+                self._functions[fname] = self.extract_function(fname)
+            return self._functions[fname](argvals, allow_recursion=allow_recursion), should_return
+
+        raise self.Exception(
+            f'Unsupported JS expression {truncate_string(expr, 20, 20) if expr != stmt else ""}', stmt)
+
+    def interpret_expression(self, expr, local_vars, allow_recursion):
+        ret, should_return = self.interpret_statement(expr, local_vars, allow_recursion)
+        if should_return:
+            raise self.Exception('Cannot return from an expression', expr)
+        return ret
+
+    def extract_object(self, objname):
+        _FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')'''
+        obj = {}
+        obj_m = re.search(
+            r'''(?x)
+                (?<!\.)%s\s*=\s*{\s*
+                    (?P<fields>(%s\s*:\s*function\s*\(.*?\)\s*{.*?}(?:,\s*)?)*)
+                }\s*;
+            ''' % (re.escape(objname), _FUNC_NAME_RE),
+            self.code)
+        if not obj_m:
+            raise self.Exception(f'Could not find object {objname}')
+        fields = obj_m.group('fields')
+        # Currently, it only supports function definitions
+        fields_m = re.finditer(
+            r'''(?x)
+                (?P<key>%s)\s*:\s*function\s*\((?P<args>(?:%s|,)*)\){(?P<code>[^}]+)}
+            ''' % (_FUNC_NAME_RE, _NAME_RE),
+            fields)
+        for f in fields_m:
+            argnames = f.group('args').split(',')
+            name = remove_quotes(f.group('key'))
+            obj[name] = function_with_repr(self.build_function(argnames, f.group('code')), f'F<{name}>')
+
+        return obj
+
+    def extract_function_code(self, funcname):
+        """ @returns argnames, code """
+        func_m = re.search(
+            r'''(?xs)
+                (?:
+                    function\s+%(name)s|
+                    [{;,]\s*%(name)s\s*=\s*function|
+                    (?:var|const|let)\s+%(name)s\s*=\s*function
+                )\s*
+                \((?P<args>[^)]*)\)\s*
+                (?P<code>{.+})''' % {'name': re.escape(funcname)},
+            self.code)
+        if func_m is None:
+            raise self.Exception(f'Could not find JS function "{funcname}"')
+        code, _ = self._separate_at_paren(func_m.group('code'))
+        return [x.strip() for x in func_m.group('args').split(',')], code
+
+    def extract_function(self, funcname):
+        return function_with_repr(
+            self.extract_function_from_code(*self.extract_function_code(funcname)),
+            f'F<{funcname}>')
+
+    def extract_function_from_code(self, argnames, code, *global_stack):
+        local_vars = {}
+        while True:
+            mobj = re.search(r'function\((?P<args>[^)]*)\)\s*{', code)
+            if mobj is None:
+                break
+            start, body_start = mobj.span()
+            body, remaining = self._separate_at_paren(code[body_start - 1:])
+            name = self._named_object(local_vars, self.extract_function_from_code(
+                [x.strip() for x in mobj.group('args').split(',')],
+                body, local_vars, *global_stack))
+            code = code[:start] + name + remaining
+        return self.build_function(argnames, code, local_vars, *global_stack)
+
+    def call_function(self, funcname, *args):
+        return self.extract_function(funcname)(args)
+
+    def build_function(self, argnames, code, *global_stack):
+        global_stack = list(global_stack) or [{}]
+        argnames = tuple(argnames)
+
+        def resf(args, kwargs={}, allow_recursion=100):
+            global_stack[0].update(itertools.zip_longest(argnames, args, fillvalue=None))
+            global_stack[0].update(kwargs)
+            var_stack = LocalNameSpace(*global_stack)
+            ret, should_abort = self.interpret_statement(code.replace('\n', ' '), var_stack, allow_recursion - 1)
+            if should_abort:
+                return ret
+        return resf