SyntaxError: JSON.parse: bad parsing

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Message#
Error type#
What went wrong?#
Examples#
JSON.parse() does not allow trailing commas#
Property names must be double-quoted strings#
Leading zeros and decimal points#
See also#

The JavaScript exceptions thrown by {{jsxref("JSON.parse()")}} occur when string failed to be parsed as JSON.

Message#

SyntaxError: JSON.parse: unterminated string literal
SyntaxError: JSON.parse: bad control character in string literal
SyntaxError: JSON.parse: bad character in string literal
SyntaxError: JSON.parse: bad Unicode escape
SyntaxError: JSON.parse: bad escape character
SyntaxError: JSON.parse: unterminated string
SyntaxError: JSON.parse: no number after minus sign
SyntaxError: JSON.parse: unexpected non-digit
SyntaxError: JSON.parse: missing digits after decimal point
SyntaxError: JSON.parse: unterminated fractional number
SyntaxError: JSON.parse: missing digits after exponent indicator
SyntaxError: JSON.parse: missing digits after exponent sign
SyntaxError: JSON.parse: exponent part is missing a number
SyntaxError: JSON.parse: unexpected end of data
SyntaxError: JSON.parse: unexpected keyword
SyntaxError: JSON.parse: unexpected character
SyntaxError: JSON.parse: end of data while reading object contents
SyntaxError: JSON.parse: expected property name or '}'
SyntaxError: JSON.parse: end of data when ',' or ']' was expected
SyntaxError: JSON.parse: expected ',' or ']' after array element
SyntaxError: JSON.parse: end of data when property name was expected
SyntaxError: JSON.parse: expected double-quoted property name
SyntaxError: JSON.parse: end of data after property name when ':' was expected
SyntaxError: JSON.parse: expected ':' after property name in object
SyntaxError: JSON.parse: end of data after property value in object
SyntaxError: JSON.parse: expected ',' or '}' after property value in object
SyntaxError: JSON.parse: expected ',' or '}' after property-value pair in object literal
SyntaxError: JSON.parse: property names must be double-quoted strings
SyntaxError: JSON.parse: expected property name or '}'
SyntaxError: JSON.parse: unexpected character
SyntaxError: JSON.parse: unexpected non-whitespace character after JSON data

Error type#

What went wrong?#

{{jsxref("JSON.parse()")}} parses a string as JSON. This string has to be valid JSON and will throw this error if incorrect syntax was encountered.

Examples#

JSON.parse() does not allow trailing commas#

Both lines will throw a SyntaxError:

```js example-bad JSON.parse("[1, 2, 3, 4,]"); JSON.parse('{"foo": 1,}'); // SyntaxError JSON.parse: unexpected character // at line 1 column 14 of the JSON data

Omit the trailing commas to parse the JSON correctly:

```js example-good
JSON.parse("[1, 2, 3, 4]");
JSON.parse('{"foo": 1}');

Property names must be double-quoted strings#

You cannot use single-quotes around properties, like 'foo'.

```js example-bad JSON.parse("{'foo': 1}"); // SyntaxError: JSON.parse: expected property name or '}' // at line 1 column 2 of the JSON data

Instead write "foo":

```js example-good
JSON.parse('{"foo": 1}');

Leading zeros and decimal points#

You cannot use leading zeros, like 01, and decimal points must be followed by at least one digit.

```js example-bad JSON.parse('{"foo": 01}'); // SyntaxError: JSON.parse: expected ',' or '}' after property value // in object at line 1 column 2 of the JSON data

JSON.parse('{"foo": 1.}'); // SyntaxError: JSON.parse: unterminated fractional number // at line 1 column 2 of the JSON data

Instead write just 1 without a zero and use at least one digit after a decimal point:

```js example-good
JSON.parse('{"foo": 1}');
JSON.parse('{"foo": 1.0}');