Chrome/FF differences in SyntaxError wording on JSON.parse()

json-syntax-error-cases.js

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/JSON_bad_parse

let errorCases = [
  {
    source: '[1, 2, 3, 4,]',
    cause: 'JSON.parse() does not allow trailing commas',
    mdn: `SyntaxError JSON.parse: unexpected character`,
    ff: `JSON.parse: unexpected character at line 1 column 13 of the JSON data`,
    node: `Unexpected token ] in JSON at position 12`
  },
  {
    source: '{"foo": 1,}',
    cause: 'JSON.parse() does not allow trailing commas',
    mdn: `SyntaxError JSON.parse: unexpected character`,
    ff: `JSON.parse: expected double-quoted property name at line 1 column 11 of the JSON data`,
    node: `Unexpected token } in JSON at position 10`,
  },
  {
    source: "{'foo': 1}",
    cause: 'Property names must be double-quoted strings',
    mdn: `SyntaxError: JSON.parse: expected property name or '}'`,
    ff: `JSON.parse: expected property name or '}' at line 1 column 2 of the JSON data`,
    node: `Unexpected token ' in JSON at position 1`
  },
  {
    source: '{"foo": 01}',
    cause: 'Leading zeros and decimal points',
    mdn: `SyntaxError: JSON.parse: expected ',' or '}' after property value`,
    ff: `JSON.parse: expected ',' or '}' after property value in object at line 1 column 10 of the JSON data`,
    node: `Unexpected number in JSON at position 9`
  },
  {
    source: '{"foo": 1.}',
    cause: 'Leading zeros and decimal points',
    mdn: `SyntaxError: JSON.parse: unterminated fractional number`,
    ff: `JSON.parse: unterminated fractional number at line 1 column 11 of the JSON data`,
    node: `Unexpected token } in JSON at position 10`
  },
  {
    source: '{"a": "b}',
    cause: 'Unterminated string',
    mdn: ``,
    ff: `JSON.parse: unterminated string at line 1 column 16 of the JSON data`,
    node: `Unexpected end of JSON input`
  },
  {
    source: '{"}',
    cause: 'Unexpected end of JSON input',
    mdn: ``,
    ff: `Unexpected end of JSON input`,
    node: `Unexpected end of JSON input`
  }
];


errorCases.forEach(errorCase => {
  try {
    JSON.parse(errorCase.source);
  } catch (e) {
    console.dir({ ...errorCase, actual: e.message });
    console.log('\n');
  }
});