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162 lines
4.2 KiB
162 lines
4.2 KiB
5 months ago
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# json-stable-stringify <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
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[![github actions][actions-image]][actions-url]
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[![coverage][codecov-image]][codecov-url]
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[![License][license-image]][license-url]
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[![Downloads][downloads-image]][downloads-url]
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[![npm badge][npm-badge-png]][package-url]
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deterministic version of `JSON.stringify()` so you can get a consistent hash from stringified results
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You can also pass in a custom comparison function.
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[](https://ci.testling.com/ljharb/json-stable-stringify)
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[](http://travis-ci.org/ljharb/json-stable-stringify)
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# example
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``` js
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const stringify = require('json-stable-stringify');
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const obj = { c: 8, b: [{ z: 6, y: 5, x: 4 }, 7], a: 3 };
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console.log(stringify(obj));
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```
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output:
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```
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{"a":3,"b":[{"x":4,"y":5,"z":6},7],"c":8}
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```
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# methods
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``` js
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const stringify = require('json-stable-stringify')
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```
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<a id="var-str--stringifyobj-opts"></a>
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## const str = stringify(obj, opts)
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Return a deterministic stringified string `str` from the object `obj`.
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## options
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### cmp
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If `opts` is given, you can supply an `opts.cmp` to have a custom comparison function for object keys.
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Your function `opts.cmp` is called with these parameters:
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``` js
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opts.cmp({ key: akey, value: avalue }, { key: bkey, value: bvalue }, { get(key): value })
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```
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For example, to sort on the object key names in reverse order you could write:
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``` js
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const stringify = require('json-stable-stringify');
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const obj = { c: 8, b: [{ z: 6, y: 5, x: 4 },7], a: 3 };
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const s = stringify(obj, function (a, b) {
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return b.key.localeCompare(a.key);
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});
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console.log(s);
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```
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which results in the output string:
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``` js
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{"c":8,"b":[{"z":6,"y":5,"x":4},7],"a":3}
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```
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Or if you wanted to sort on the object values in reverse order, you could write:
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``` js
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const stringify = require('json-stable-stringify');
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const obj = { d: 6, c: 5, b: [{ z: 3, y: 2, x: 1 }, 9], a: 10 };
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const s = stringify(obj, function (a, b) {
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return a.value < b.value ? 1 : -1;
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});
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console.log(s);
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```
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which outputs:
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``` js
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{"d":6,"c":5,"b":[{"z":3,"y":2,"x":1},9],"a":10}
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```
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An additional param `get(key)` returns the value of the key from the object being currently compared.
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### space
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If you specify `opts.space`, it will indent the output for pretty-printing.
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Valid values are strings (e.g. `{space: \t}`) or a number of spaces
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(`{space: 3}`).
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For example:
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```js
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const obj = { b: 1, a: { foo: 'bar', and: [1, 2, 3] } };
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const s = stringify(obj, { space: ' ' });
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console.log(s);
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```
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which outputs:
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```
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{
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"a": {
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"and": [
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1,
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2,
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3
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],
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"foo": "bar"
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},
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"b": 1
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}
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```
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### replacer
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The replacer parameter is a function `opts.replacer(key, value)` that behaves the same as the replacer
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[from the core JSON object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_native_JSON#The_replacer_parameter).
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# install
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With [npm](https://npmjs.org) do:
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```
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npm install json-stable-stringify
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```
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# license
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MIT
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[package-url]: https://npmjs.org/package/json-stable-stringify
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[npm-version-svg]: https://versionbadg.es/ljharb/json-stable-stringify.svg
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[deps-svg]: https://david-dm.org/ljharb/json-stable-stringify.svg
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[deps-url]: https://david-dm.org/ljharb/json-stable-stringify
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[dev-deps-svg]: https://david-dm.org/ljharb/json-stable-stringify/dev-status.svg
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[dev-deps-url]: https://david-dm.org/ljharb/json-stable-stringify#info=devDependencies
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[npm-badge-png]: https://nodei.co/npm/json-stable-stringify.png?downloads=true&stars=true
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[license-image]: https://img.shields.io/npm/l/json-stable-stringify.svg
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[license-url]: LICENSE
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[downloads-image]: https://img.shields.io/npm/dm/json-stable-stringify.svg
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[downloads-url]: https://npm-stat.com/charts.html?package=json-stable-stringify
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[codecov-image]: https://codecov.io/gh/ljharb/json-stable-stringify/branch/main/graphs/badge.svg
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[codecov-url]: https://app.codecov.io/gh/ljharb/json-stable-stringify/
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[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/ljharb/json-stable-stringify
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[actions-url]: https://github.com/ljharb/json-stable-stringify/actions
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