Mar 31, 2024
diff --git a/Doc/library/json.rst b/Doc/library/json.rst
      This can be used to decode a JSON document from a string that may have
      extraneous data at the end.

   .. versionchanged:: 3.14
      Now ignores any leading whitespace instead of returning an error


 .. class:: JSONEncoder(*, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, default=None)

diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
        containing a JSON document).

        """
        obj, end = self.raw_decode(s, idx=_w(s, 0).end())
        obj, end = self.raw_decode(s)
        end = _w(s, end).end()
        if end != len(s):
            raise JSONDecodeError("Extra data", s, end)
        return obj

    def raw_decode(self, s, idx=0):
    def raw_decode(self, s, idx=0, _w=WHITESPACE.match):
        """Decode a JSON document from ``s`` (a ``str`` beginning with
        a JSON document) and return a 2-tuple of the Python
        representation and the index in ``s`` where the document ended.
        Whitespace at the beginning of the document will be ignored.

        Optionally, ``idx`` can be used to specify an offset in ``s``
        where the document begins.

        This can be used to decode a JSON document from a string that may
        have extraneous data at the end.

        """
        try:
            obj, end = self.scan_once(s, idx)
            obj, end = self.scan_once(s, idx=_w(s, idx).end())
        except StopIteration as err:
            raise JSONDecodeError("Expecting value", s, err.value) from None
        return obj, end
diff --git a/Lib/test/test_json/test_decode.py b/Lib/test/test_json/test_decode.py
            with self.assertRaises(ValueError):
                self.loads('1' * (maxdigits + 1))

 class TestRawDecode:
    def test_whitespace(self):
        decoder = self.json.JSONDecoder()
        self.assertEqual(decoder.raw_decode(' {}'), ({}, 3))
        self.assertEqual(decoder.raw_decode('  []'), ([], 4))
        self.assertEqual(decoder.raw_decode('   ""'), ('', 5))
        s = '  {   "key"    :    "value"    ,  "k":"v"    } \n' \
            ' { "key": "value",  "k" :"v"} '
        val1, n1 = decoder.raw_decode(s)
        val2, n2 = decoder.raw_decode(s[n1:])
        self.assertEqual(val1, {"key":"value", "k":"v"})
        self.assertEqual(val2, {"key":"value", "k":"v"})

 class TestPyDecode(TestDecode, PyTest): pass
 class TestCDecode(TestDecode, CTest): pass
 class TestPyRawDecode(TestRawDecode, PyTest): pass
 class TestCRawDecode(TestRawDecode, CTest): pass
diff --git a/Misc/NEWS.d/next/Library/2024-04-22-07-05-05.gh-issue-59598.LyEKW3.rst b/Misc/NEWS.d/next/Library/2024-04-22-07-05-05.gh-issue-59598.LyEKW3.rst
 Ignore leading whitespace in :func:`JSONDecoder.raw_decode`
Original file line number	Diff line number	Diff line change
Expand Up		@@ -402,6 +402,9 @@ Encoders and Decoders
		This can be used to decode a JSON document from a string that may have
		extraneous data at the end.

		.. versionchanged:: 3.14
		Now ignores any leading whitespace instead of returning an error


		.. class:: JSONEncoder(*, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, default=None)

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -341,23 +341,27 @@ def decode(self, s, _w=WHITESPACE.match):
		containing a JSON document).

		"""
		obj, end = self.raw_decode(s, idx=_w(s, 0).end())
		obj, end = self.raw_decode(s)
		end = _w(s, end).end()
		if end != len(s):
		raise JSONDecodeError("Extra data", s, end)
		return obj

		def raw_decode(self, s, idx=0):
		def raw_decode(self, s, idx=0, _w=WHITESPACE.match):
		"""Decode a JSON document from ``s`` (a ``str`` beginning with
		a JSON document) and return a 2-tuple of the Python
		representation and the index in ``s`` where the document ended.
		Whitespace at the beginning of the document will be ignored.

		Optionally, ``idx`` can be used to specify an offset in ``s``
		where the document begins.

		This can be used to decode a JSON document from a string that may
		have extraneous data at the end.

		"""
		try:
		obj, end = self.scan_once(s, idx)
		obj, end = self.scan_once(s, idx=_w(s, idx).end())
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		except StopIteration as err:
		raise JSONDecodeError("Expecting value", s, err.value) from None
		return obj, end
Original file line number	Diff line number	Diff line change
Expand Up		@@ -124,6 +124,20 @@ def test_limit_int(self):
		with self.assertRaises(ValueError):
		self.loads('1' * (maxdigits + 1))

		class TestRawDecode:
		def test_whitespace(self):
		decoder = self.json.JSONDecoder()
		self.assertEqual(decoder.raw_decode(' {}'), ({}, 3))
		self.assertEqual(decoder.raw_decode(' []'), ([], 4))
		self.assertEqual(decoder.raw_decode(' ""'), ('', 5))
		s = ' { "key" : "value" , "k":"v" } \n' \
		' { "key": "value", "k" :"v"} '
		val1, n1 = decoder.raw_decode(s)
		val2, n2 = decoder.raw_decode(s[n1:])
		self.assertEqual(val1, {"key":"value", "k":"v"})
		self.assertEqual(val2, {"key":"value", "k":"v"})

		class TestPyDecode(TestDecode, PyTest): pass
		class TestCDecode(TestDecode, CTest): pass
		class TestPyRawDecode(TestRawDecode, PyTest): pass
		class TestCRawDecode(TestRawDecode, CTest): pass
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Ignore leading whitespace in :func:`JSONDecoder.raw_decode`