JS Object Literal to Strict JSON Converter

What changes on the way to JSON

Some JavaScript values have no JSON form. A property set to undefined disappears, and undefined inside an array becomes null. Hex numbers and numeric separators such as 1_000 are written as ordinary decimals. Template literals become plain strings, with any ${…} left as literal text. Integers beyond 9,007,199,254,740,991 lose precision, because the value passes through a JavaScript number; quote long IDs as strings in the source first.

Data only, never code

The converter reads the literal as data and never runs it, so a pasted snippet cannot do anything. The cost is that anything computed is refused: variables, function calls, new Date(), spread syntax, NaN, and Infinity. Replace each with the value you want in the JSON, then convert again; the error names the line and column to look at. A leading const name = or export default is removed automatically. The JSON validator confirms the result before it goes into a config file.

How to use it

1. Paste a JS object snippet.
2. Set formatting indentation.
3. Copy the valid JSON output.

Privacy & limitations

Parsing and formatting take place 100% in your local browser environment.