Parse JSON with large numbers javascript

Question

I'm getting a JSON object that includes a long type value from an API response. Since javascript can't handle 64bit numbers, when executing JSON.parse on the response it rounds the number to the maximum value javascript can handle.

API response:

    {
       "subject": "subjectTitle",
       "longNumberKey": 7356270823847851521,
    }

When parsing this object to JSON, longNumberKey value would be 7356270823847852000 instead of 7356270823847851521. A solution would be to represent this value as a string but I can't control the API response for that.

What should it return instead? Javascript numbers simply don't have enough precision to represent that number accurately. — Barmar, Feb 29 '16 at 22:36
I know that, but I need to display this value accurately, I don't need to do any arithmetic operations with this number. — Avraham, Feb 29 '16 at 22:39
Javascript can't store numbers like this. It doesn't matter what you want to do with it. — Barmar, Feb 29 '16 at 22:40
We both know this fact. The question is what would be a solution for that. Do you have any idea ? Maybe other approach than JSON.parse ? — Avraham, Feb 29 '16 at 22:45
Write your own, custom JSON parser that parses numbers as strings instead of numbers. — Barmar, Feb 29 '16 at 22:46
That is exactly what I thought of. Is the native Parse function code accessible to view ? — Avraham, Feb 29 '16 at 22:49
@Barmar curious what approach would be...even in a `replacer` wouldn't number get lost? — charlietfl, Feb 29 '16 at 22:51
**json-bignum** https://www.npmjs.com/package/json-bignum see below — ralf htp, Feb 29 '16 at 22:51
@charlietfl If it returns numbers as strings, it shouldn't lose anything. — Barmar, Feb 29 '16 at 22:52
@Barmar ok..so in other words because it is still in a json string it would be considered string without quotes in `replacer`? — charlietfl, Feb 29 '16 at 22:54
http://stackoverflow.com/questions/1379934/large-numbers-erroneously-rounded-in-javascript — Niklesh Raut, Feb 29 '16 at 22:55
@Barmar ..oops meant `reviver` as in `JSON.parse(string, reviver)` — charlietfl, Feb 29 '16 at 23:05
I wasn't suggesting a reviver, I was suggesting `function myJSONparse(string) { ... }` — Barmar, Feb 29 '16 at 23:05
A reviver will not help, it gets the parsed values. Anyway, it seems like the `json-bignum` library provides a solution to my case. Thank you all. — Avraham, Mar 01 '16 at 12:07

ralf htp · Accepted Answer · 2016-02-29T22:48:11.890

3

-----> json-bignum https://www.npmjs.com/package/json-bignum <------ JSON parser !

GMP (GNU multiple precision) with javascript https://github.com/jtobey/javascript-bignum/blob/master/src/gmp-example.html

gmp.js https://github.com/kripken/gmp.js?MobileOptOut=1

edited Feb 29 '16 at 22:48

answered Feb 29 '16 at 22:39

ralf htp

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Does it have a JSON parser? He doesn't need to do arithmetic on the numbers, he just needs to parse the JSON. – Barmar Feb 29 '16 at 22:41

Parse JSON with large numbers javascript

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