README.md
1# fast-json-stable-stringify
2
3Deterministic `JSON.stringify()` - a faster version of [@substack](https://github.com/substack)'s json-stable-strigify without [jsonify](https://github.com/substack/jsonify).
4
5You can also pass in a custom comparison function.
6
7[](https://travis-ci.org/epoberezkin/fast-json-stable-stringify)
8[](https://coveralls.io/github/epoberezkin/fast-json-stable-stringify?branch=master)
9
10# example
11
12``` js
13var stringify = require('fast-json-stable-stringify');
14var obj = { c: 8, b: [{z:6,y:5,x:4},7], a: 3 };
15console.log(stringify(obj));
16```
17
18output:
19
20```
21{"a":3,"b":[{"x":4,"y":5,"z":6},7],"c":8}
22```
23
24
25# methods
26
27``` js
28var stringify = require('fast-json-stable-stringify')
29```
30
31## var str = stringify(obj, opts)
32
33Return a deterministic stringified string `str` from the object `obj`.
34
35
36## options
37
38### cmp
39
40If `opts` is given, you can supply an `opts.cmp` to have a custom comparison
41function for object keys. Your function `opts.cmp` is called with these
42parameters:
43
44``` js
45opts.cmp({ key: akey, value: avalue }, { key: bkey, value: bvalue })
46```
47
48For example, to sort on the object key names in reverse order you could write:
49
50``` js
51var stringify = require('fast-json-stable-stringify');
52
53var obj = { c: 8, b: [{z:6,y:5,x:4},7], a: 3 };
54var s = stringify(obj, function (a, b) {
55 return a.key < b.key ? 1 : -1;
56});
57console.log(s);
58```
59
60which results in the output string:
61
62```
63{"c":8,"b":[{"z":6,"y":5,"x":4},7],"a":3}
64```
65
66Or if you wanted to sort on the object values in reverse order, you could write:
67
68```
69var stringify = require('fast-json-stable-stringify');
70
71var obj = { d: 6, c: 5, b: [{z:3,y:2,x:1},9], a: 10 };
72var s = stringify(obj, function (a, b) {
73 return a.value < b.value ? 1 : -1;
74});
75console.log(s);
76```
77
78which outputs:
79
80```
81{"d":6,"c":5,"b":[{"z":3,"y":2,"x":1},9],"a":10}
82```
83
84### cycles
85
86Pass `true` in `opts.cycles` to stringify circular property as `__cycle__` - the result will not be a valid JSON string in this case.
87
88TypeError will be thrown in case of circular object without this option.
89
90
91# install
92
93With [npm](https://npmjs.org) do:
94
95```
96npm install fast-json-stable-stringify
97```
98
99
100# benchmark
101
102To run benchmark (requires Node.js 6+):
103```
104node benchmark
105```
106
107Results:
108```
109fast-json-stable-stringify x 17,189 ops/sec ±1.43% (83 runs sampled)
110json-stable-stringify x 13,634 ops/sec ±1.39% (85 runs sampled)
111fast-stable-stringify x 20,212 ops/sec ±1.20% (84 runs sampled)
112faster-stable-stringify x 15,549 ops/sec ±1.12% (84 runs sampled)
113The fastest is fast-stable-stringify
114```
115
116
117# license
118
119[MIT](https://github.com/epoberezkin/fast-json-stable-stringify/blob/master/LICENSE)
120
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