Double comma in a JSON array
Two commas in a row, leaving an empty slot. JavaScript allows array holes; JSON does not.
The input
[1,,2][1, null, 2]How to fix it
Remove the extra comma, or write `null` if the empty slot is meaningful.
Usually the residue of deleting an element without deleting its separator.
What each parser reports
Every message below was captured by running this exact input through the parser named. 17 of 21 parsers rejected it; 4 accepted it.
| Parser | Exact message |
|---|---|
| CPython json.loads CPython 3.12.3 | Expecting value: line 1 column 4 (char 3)what this message means → |
| encoding/json Unmarshal Go go1.22.2 | invalid character ',' looking for beginning of valuewhat this message means → |
| Gson Java 21.0.12 | accepted — no error |
| Gson JsonParser (lenient off) Java 21.0.12 | accepted — no error |
| hjson Node.js 22.22.2 | Found a punctuator character ',' when expecting a quoteless string (check your syntax) at line 1,3 >>>1,,2] ...what this message means → |
| Jackson ObjectMapper Java 21.0.12 | Unexpected character (',' (code 44)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false')what this message means → |
| JavaScriptCore JSON.parse JavaScriptCore (Bun 1.4.1) | JSON Parse error: Unexpected token ','what this message means → |
| json-bigint Node.js 22.22.2 | Unexpected ',' |
| JSON5 Node.js 22.22.2 | JSON5: invalid character ',' at 1:4what this message means → |
| JSON::PP Perl 5.038002 | malformed JSON string, neither array, object, number, string or atom, at character offset 3 (before ",2]")what this message means → |
| json_decode PHP 8.3.6 | Syntax error |
| Newtonsoft.Json JsonConvert Newtonsoft.Json 13.0.3 on .NET 8.0.30 | accepted — no error |
| Newtonsoft.Json JsonTextReader Newtonsoft.Json 13.0.3 on .NET 8.0.30 | accepted — no error |
| orjson CPython 3.12.3 | unexpected character, expected a JSON value: line 1 column 4 (char 3)what this message means → |
| Ruby JSON.parse Ruby 3.2.3 | unexpected token at ',2]' |
| serde_json::from_str Rust (serde_json 1.x) | expected value at line 1 column 4what this message means → |
| SpiderMonkey JSON.parse SpiderMonkey 115 | JSON.parse: unexpected character at line 1 column 4 of the JSON datawhat this message means → |
| System.Text.Json Deserialize .NET 8.0.30 | ',' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 3.what this message means → |
| System.Text.Json JsonDocument .NET 8.0.30 | ',' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 3.what this message means → |
| ujson CPython 3.12.3 | Expected object or value |
| V8 JSON.parse Node.js 22.22.2 | Unexpected token ',', "[1,,2]" is not valid JSONwhat this message means → |
What the specification says
The exact sections that govern this error. Descriptions are our paraphrase; follow the links for the normative text.
| Body | Section |
|---|---|
| IETF | An array is square brackets around zero or more values, with elements separated by commas. |
| Ecma International | Gives the array grammar; values are separated by commas. |
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