Javascript - convert an EXTRA LARGE Number to string in JSON before the default parsing

Question

As I mentioned in THIS QUESTION, I have problem when getting the response from the server.

I receive an array of objects with these attributes:

[{
"Id": 143187001116603,   // VERY big number which I want to convert it to string
"Name": "تملی612",   // string
"Title": "تسهیلات مسکن بانک ملی-اسفند96",   // string
"InsCode": "IRO6MELZ96C1"   // string
},
...
]

Any simple way to convert a specified type (Number) to string in a JSON file?

I see the replacer argument in JSON.stringify() but I have no idea how to use that...

UPDATE

One of those Ids, is: 9481703061634967 but JS convert that to 9481703061634968!

UPDATE

As Jonas H said in this answer, JS run the default parsing and that's why i lose my real Id value!

Any idea?

score 5 · Accepted Answer · edited Jun 23 '20 at 03:39

5

Transform the response to string, then apply a repalce with a regex to convert Id field to string type:

const axios = require('axios');

axios.get(url, { transformResponse: [data => data] }).then(response => {
  let parsed = JSON.parse(response.data.replace(/"Id":(\d+),/g, '"Id":"$1",'));
  console.log(parsed);
});

edited Jun 23 '20 at 03:39

MohamadKh75

2,582
5
28
54

answered Oct 27 '18 at 14:49

Hamidreza Kalantari

483
2
10

Jonas Høgh · Answer 2 · 2018-10-27T14:17:44.597

3

Assuming that you receive the data as a Json string with the numbers inside them, there is no way to preserve the data using JSON.parse. Even if you use the second argument to add a transformation function, it will only be run after the default parsing has parsed the numbers with a loss of information in case of large numbers. You need to manipulate the string directly to wrap the number in quotes using e.g. a regular expression.

You can also use the json-bigint npm package: https://www.npmjs.com/package/json-bigint

edited Oct 27 '18 at 14:17

answered Oct 27 '18 at 14:09

Jonas Høgh

10,358
1
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Thanks for info - Would you please provide some code? any way to do this before the default parsing? – MohamadKh75 Oct 27 '18 at 14:11
Try the link I just added, that's probably better than rolling your own. – Jonas Høgh Oct 27 '18 at 14:18
Thanks - Can I use this with `Axios`? or I have to use `fetch()` and save the response in `JSONbig`? – MohamadKh75 Oct 27 '18 at 14:21
I'm unsure whether axios interceptors or responseTransform can be used before the automatic Json parse step, but you might want to try them out. – Jonas Høgh Oct 27 '18 at 15:10
It's working! the `transformResponse` run before automatic JSON parse! – MohamadKh75 Oct 27 '18 at 15:45
Glad I could help you out – Jonas Høgh Oct 27 '18 at 15:50

Jamal Hassouni · Answer 3 · 2018-10-27T13:58:13.787

0

you can use replacer in JSON.stringify() like :

var obj  = {
"Id": 143187001116603,   // VERY big number which I want to convert it to string
"Name": "تملی612",   // string
"Title": "تسهیلات مسکن بانک ملی-اسفند96",   // string
"InsCode": "IRO6MELZ96C1"   // string
};


function replacer(name, val) {
    // convert Number to string
    if ( val && val.constructor === Number ) {
        return val.toString();
    } else {
        return val; // return as is
    }
};

 JSON.stringify(obj, replacer, 4);

// result

{
    "Id": "143187001116603",
    "Name": "تملی612",
    "Title": "تسهیلات مسکن بانک ملی-اسفند96",
    "InsCode": "IRO6MELZ96C1"
}

edited Oct 27 '18 at 13:58

answered Oct 27 '18 at 13:48

Jamal Hassouni

81
2
9

The value of `Id` is changed before... See the **update** please – MohamadKh75 Oct 27 '18 at 14:03
@MohamadKh75 this is because of number limit in JavaScript. – Jamal Hassouni Oct 27 '18 at 14:07
I know and that's why i'm asking for a way to convert it to a `string` – MohamadKh75 Oct 27 '18 at 14:08
JavaScript numbers are Double Precision Floats; the largest integer that can be precisely stored is 2^53 (9007199254740992). If you actually need it in a number you have some fun math ahead of you, or you can use a library such as [big.js](https://github.com/MikeMcl/big.js) – Jamal Hassouni Oct 27 '18 at 14:10
I really don't need that in `Number` format! i just want to save that as `string` before default parsing round it! – MohamadKh75 Oct 27 '18 at 14:12

score 0 · Answer 4 · answered Oct 27 '18 at 14:10

function replacer(key, value) {
  // Filtering out properties
  if (key === 'Id') {
    return value.toString();
  }
  return value;
}

const t = [{
    "Id": 143187001116603, // VERY big number which I want to convert it to string
    "Name": "تملی612", // string
    "Title": "تسهیلات مسکن بانک ملی-اسفند96", // string
    "InsCode": "IRO6MELZ96C1" // string
  },
  {
    "Id": 9481703061634967, // VERY big number which I want to convert it to string
    "Name": "تملی232", // string
    "Title": "تسهیلات مسکن بانک ملی-اسفن216", // string
    "InsCode": "IRO6MSDZ96C1" // string
  }
]
const stringifiedValue = JSON.stringify(t, replacer)
console.log(JSON.parse(stringifiedValue))

Try this using replacer callback for JSON.stringify.

Feedbacks welcome.

Javascript - convert an EXTRA LARGE Number to string in JSON before the default parsing

UPDATE

UPDATE

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