json-stringify-deterministic
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deterministic version of JSON.stringify() so you can get a consistent hash from stringified results.
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# json-stringify-deterministic
[](https://coveralls.io/github/Kikobeats/json-stringify-deterministic)
[](https://www.npmjs.org/package/json-stringify-deterministic)
> Deterministic version of `JSON.stringify()`, so you can get a consistent hash from stringified results.
Similar to [json-stable-stringify](https://github.com/substack/json-stable-stringify) *but*:
- No Dependencies. Minimal as possible.
- Better cycles detection.
- Support serialization for object without `.toJSON` (such as `RegExp`).
- Provides built-in TypeScript declarations.
## Install
```bash
npm install json-stringify-deterministic --save
```
## Usage
```js
const stringify = require('json-stringify-deterministic')
const obj = { c: 8, b: [{ z: 6, y: 5, x: 4 }, 7], a: 3 }
console.log(stringify(obj))
// => {"a":3,"b":[{"x":4,"y":5,"z":6},7],"c":8}
```
## API
### stringify(<obj>, [opts])
#### obj
*Required*<br>
Type: `object`
The input `object` to be serialized.
#### opts
##### opts.stringify
Type: `function`
Default: `JSON.stringify`
Determinate how to stringify primitives values.
##### opts.cycles
Type: `boolean`
Default: `false`
Determinate how to resolve cycles.
Under `true`, when a cycle is detected, `[Circular]` will be inserted in the node.
##### opts.compare
Type: `function`
Custom comparison function for object keys.
Your function `opts.compare` is called with these parameters:
``` js
opts.cmp({ key: akey, value: avalue }, { key: bkey, value: bvalue })
```
For example, to sort on the object key names in reverse order you could write:
``` js
const stringify = require('json-stringify-deterministic')
const obj = { c: 8, b: [{z: 6,y: 5,x: 4}, 7], a: 3 }
const objSerializer = stringify(obj, function (a, b) {
return a.key < b.key ? 1 : -1
})
console.log(objSerializer)
// => {"c":8,"b":[{"z":6,"y":5,"x":4},7],"a":3}
```
Or if you wanted to sort on the object values in reverse order, you could write:
```js
const stringify = require('json-stringify-deterministic')
const obj = { d: 6, c: 5, b: [{ z: 3, y: 2, x: 1 }, 9], a: 10 }
const objtSerializer = stringify(obj, function (a, b) {
return a.value < b.value ? 1 : -1
})
console.log(objtSerializer)
// => {"d":6,"c":5,"b":[{"z":3,"y":2,"x":1},9],"a":10}
```
##### opts.space
Type: `string`<br>
Default: `''`
If you specify `opts.space`, it will indent the output for pretty-printing.
Valid values are strings (e.g. `{space: \t}`). For example:
```js
const stringify = require('json-stringify-deterministic')
const obj = { b: 1, a: { foo: 'bar', and: [1, 2, 3] } }
const objSerializer = stringify(obj, { space: ' ' })
console.log(objSerializer)
// => {
// "a": {
// "and": [
// 1,
// 2,
// 3
// ],
// "foo": "bar"
// },
// "b": 1
// }
```
##### opts.replacer
Type: `function`<br>
The replacer parameter is a function `opts.replacer(key, value)` that behaves
the same as the replacer
[from the core JSON object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_native_JSON#The_replacer_parameter).
## Related
- [sort-keys-recursive](https://github.com/Kikobeats/sort-keys-recursive): Sort the keys of an array/object recursively.
## License
MIT © [Kiko Beats](https://github.com/Kikobeats).