I have added this note, thanks! In the blog I am mostly trying to show the behavior you get using the (maybe defacto) stdlib with its default configuration, but this is useful data to call out.
To wit, Python's json module has `parse_float` and `parse_int` hooks:
https://docs.python.org/3/library/json.html#encoders-and-dec...
Example:
>>> json.loads('{"int":12345,"float":123.45}', parse_int=str, parse_float=str)
{'int': '12345', 'float': '123.45'}
This example on MDN seems to indicate that you can, am I misunderstanding it?
const bigJSON = '{"gross_gdp": 12345678901234567890}';
const bigObj = JSON.parse(bigJSON, (key, value, context) => {
if (key === "gross_gdp") {
// Ignore the value because it has already lost precision
return BigInt(context.source);
}
return value;
});
The optional `context` parameter is a tc39 proposal. The feature compatibility matrix on the bottom of the MDN page is really confusing because it's showing only when `JSON.parse` was added, not whether the optional `context` parameter is supported.
I've confirmed it's available in:
- V8 11.4.31
- Node 20.12.0 (with `--harmony`)
- Node 21.7.1 (without requiring `--harmony`)
- Chrome 123.0.6312.107
Firefox 124.0.2 (ironically)
Safari 17.3.1
https://tc39.es/proposal-json-parse-with-source/
https://github.com/tc39/proposal-json-parse-with-source
This issue links to the various browser engine tracking bugs:
https://github.com/tc39/proposal-json-parse-with-source/issu...
Which are:
• Chrome/V8: https://bugs.chromium.org/p/v8/issues/detail?id=12955
• Firefox/SpiderMonkey: https://bugzilla.mozilla.org/show_bug.cgi?id=1658310
• Safari/JavaScriptCore: https://bugs.webkit.org/show_bug.cgi?id=248031
With Zod, you can use z.bigint() parser. If you take the "parse any JSON" snippet https://zod.dev/?id=json-type and change z.number() to z.bigint(), it should do what you are looking for.