Why JSON Is Stricter Than a JavaScript Object Literal

JSON is data, not executable JavaScript

JSON represents objects, arrays, strings, numbers, booleans, and null. Object keys and strings use double quotes. Comments, functions, undefined, and trailing commas are not part of standard JSON syntax.

That strictness helps independent systems exchange data consistently. A file that looks nearly correct to a JavaScript developer can still fail when parsed as JSON.

Diagnose the actual input

When a parser reports an error, inspect the nearby punctuation and quoting first. Check whether a string contains an unescaped quote, whether a comma is missing, or whether a comment was copied into the document. Formatting valid JSON makes nesting easier to scan but does not repair ambiguous or invalid syntax automatically.

CalcPool's JSON inspection utility uses the browser's parser to validate before formatting. Keep credentials and production secrets out of public debugging tools and shared devices, even when processing is local.