Unable to parse values larger than 1.7976931348623157E+308

[SebastianG77]

Hi,

when trying to parse a JSON-String which contains a very very big number, I get the following error message: "Bad number". The reason is, that you use isFinite() to check if the number is a finite one. However, according to the specification, Infinity is determined, as following:

"Infinity is displayed when a number exceeds the upper limit of the floating point numbers, which is 1.797693134862315E+308."

As a result, whenever a numeric value that will be parsed is larger than 1.797693134862315E+308, json-bigint is unable to parse the JSON file.

Nevertheless, bignumber.js also has a function isFinite(), which is able to handle values larger than 1.797693134862315E+308. Since from my point of view, this module should be used to parse JSON-files containing any numeric value, I would appreciate if the currently used function isFinite() will be replaced by the function isFinite() of bignumber.js. Find the different results of these function in the following example:

const BigNumber = require('bignumber.js');

console.log(isFinite(1.797693134862316E+308)) // false

console.log(BigNumber('1.797693134862316E+308').isFinite()) //true

I also added a small example, where you can see the value 3e+500 will not be parsed appropriately with json-bigint. However, when using the standard JSON parser, the value can be parsed, even though the returned value is of course incorrect.

var JSONbig = require('json-bigint')

let veryBigDecimal = `3e+500`

try {
    let jsonBigResult = JSONbig.parse(veryBigDecimal)
    console.log(`JSONbig result: ${jsonBigResult.toString()}`)
} catch (e) {
    console.log(`JSONbig error thrown: ${e.message}`)
}

try {
    let jsonResult = JSON.parse(veryBigDecimal)
    console.log(`JSON result: ${jsonResult.toString()}`)
} catch (e) {
    console.log(`JSON error thrown: ${e.message}`)
}

[sidorares]

Hi @SebastianG77 , your suggestions seem good to me. Would you be able to volunteer to make this change and submit PR?

[SebastianG77]

Alright, I can fix it, but I am not sure whether I will be able to do it before next weekend. Will send you a pull request as soon as I finished.

[Almenon]

I also ran into this error :/

[Almenon]

but this error would dissapear with native bignumbers right? @nickkolok do you still get this error in your PR?

[nickkolok]

@Almenon I'm afraid no.

> BigInt("1e+500");
Thrown:
SyntaxError: Cannot convert 1e+500 to a BigInt

> BigInt("1E+1");
Thrown:
SyntaxError: Cannot convert 1E+1 to a BigInt

[nickkolok]

@Almenon I believe that the appropriate solution is to pass any number-like string to a user-defined function and the deal with the stuff which the function returns.

[SebastianG77]

Hey guys,

I am afraid I might lack of context regarding your discussion, but I also fixed this error in this PR: https://github.com/sidorares/json-bigint/pull/26 . I also published my changes to npm (https://www.npmjs.com/package/true-json-bigint) as I needed them at that time. Feel free to try them out and give some feedback. Let me know if your problems still appear while using this package.