json-web3


BigInt-safe JSON serialization and deserialization for Web3 data.

Install

``bash
pnpm add json-web3


or

npm i json-web3

or

yarn add json-web3
`

Usage

`ts
import jsonWeb3 from 'json-web3'

const payload = {
balance: 1234567890123456789n,
decimals: 18n,
u8Array: new Uint8Array([1, 2, 3, 255]),
u16Array: new Uint16Array([1, 2, 3, 255]),
bigIntArray: new BigInt64Array([18446744073709551615n, 2n, 3n, 255n]),
createdAt: new Date('2020-01-02T03:04:05.006Z'),
ids: new Set([123, 456]),
headers: new Map([['hello', 'world']]),
re: /([^\s]+)/g,
url: new URL('https://example.com/'),
fn: function echo(arg) {
return arg
},
}

const text = jsonWeb3.stringify(payload)
// => {"balance":{"__@json.bigint__":"1234567890123456789"},"decimals":{"__@json.bigint__":"18"},"u8Array":{"__@json.typedarray__":{"type":"Uint8Array","bytes":"0x010203ff"}},"u16Array":{"__@json.typedarray__":{"type":"Uint16Array","bytes":"0x010002000300ff00"}},"bigIntArray":{"__@json.typedarray__":{"type":"BigInt64Array","bytes":"0xffffffffffffffff02000000000000000300000000000000ff00000000000000"}}}

const restored = jsonWeb3.parse(text)
/* =>
{
balance: 1234567890123456789n,
decimals: 18n,
u8Array: Uint8Array(4) [1, 2, 3, 255]...,
u16Array: Uint16Array(4)...,
bigIntArray: BigInt64Array(4)...,
createdAt: Date(...),
ids: Set(2) {...},
headers: Map(1) {...},
re: /([^\s]+)/g,
url: URL(...),
fn: undefined
}
*/

const textUnsafe = jsonWeb3.stringify_UNSAFE(payload)
const restoredUnsafe = jsonWeb3.parse_UNSAFE(textUnsafe)
// restoredUnsafe.fn is a callable function
`

Full example

`ts
import jsonWeb3 from 'json-web3'

window.JSON = jsonWeb3 // Yes, you can replace it directly; it is fully compatible.
`

API (Fully compatible with native globalThis.JSON)

- stringify(value, replacer?, space?)
- parse(text, reviver?)
- stringify_UNSAFE(value, replacer?, space?) (serializes Function payloads)
- parse_UNSAFE(text, reviver?) (revives Function payloads via new Function(...))

Type support

| type | supported by standard JSON? | supported by json-web3? |
| ------------------- | --------------------------- | ------------------------------------- |
| string | ✅ | ✅ |
| number | ✅ | ✅ |
| boolean | ✅ | ✅ |
| null | ✅ | ✅ |
| Array | ✅ | ✅ |
| Object | ✅ | ✅ |
| undefined | ❌ | ❌ |
| Infinity | ❌ | ✅ |
| -Infinity | ❌ | ✅ |
| NaN | ❌ | ✅ |
| BigInt | ❌ | ✅ |
| Date | ❌ | ✅ |
| RegExp | ❌ | ✅ |
| Set | ❌ | ✅ |
| Map | ❌ | ✅ |
| URL | ❌ | ✅ |
| ArrayBuffer | ❌ | ✅ |
| Uint8Array | ❌ | ✅ |
| Uint8ClampedArray | ❌ | ✅ |
| Uint16Array | ❌ | ✅ |
| Uint32Array | ❌ | ✅ |
| Int8Array | ❌ | ✅ |
| Int16Array | ❌ | ✅ |
| Int32Array | ❌ | ✅ |
| Float16Array | ❌ | ✅ |
| Float32Array | ❌ | ✅ |
| Float64Array | ❌ | ✅ |
| BigInt64Array | ❌ | ✅ |
| BigUint64Array | ❌ | ✅ |
| Function | ❌ | ✅ ⚠️(use UNSAFE api, it's dangerous) |

Note

- bigint values are encoded as objects: {"__@json.bigint__":""}.
- Non-finite numbers (NaN, Infinity, -Infinity) are encoded as {"__@json.number__":""}.
- Date values are encoded as {"__@json.date__":}.
- Map values are encoded as {"__@json.map__":[[k,v],...]} and Set values as {"__@json.set__":[...]}.
- RegExp values are encoded as {"__@json.regexp__":{"source":"...","flags":"..."}}.
- URL values are encoded as {"__@json.url__":"..."}.
- Function values are encoded as {"__@json.function__":""} by stringify_UNSAFE and are only revived by parse_UNSAFE using new Function(...) (using the UNSAFE function pair is dangerous; make sure your data is trusted).
- ArrayBuffer values are encoded as {"__@json.arraybuffer__":{"bytes":"0x..."}} and decoded back to ArrayBuffer.
- Node Buffer JSON shapes and typed arrays are encoded as {"__@json.typedarray__":{"type":"","bytes":"0x..."}} and decoded back to the original typed array (Uint8Array, Uint8ClampedArray, Uint16Array, Uint32Array, Int8Array, Int16Array, Int32Array, Float32Array, Float64Array, BigInt64Array, BigUint64Array).

Compared to libraries that require eval-based parsing (for example, serialize-javascript`), this approach is generally safer and more efficient.

RFC (Serialization Format)

To enable cross-language interoperability, the serialization format is specified
in RFC.md. It defines the canonical tag objects, payload shapes, validation
rules, and UNSAFE function handling.