fast-json-stable-stringify

Deterministic JSON.stringify() - a faster version of @substack's json-stable-strigify without jsonify.

You can also pass in a custom comparison function.

example

var stringify = require('fast-json-stable-stringify');
var obj = { c: 8, b: [{z:6,y:5,x:4},7], a: 3 };
console.log(stringify(obj));

output:

{"a":3,"b":[{"x":4,"y":5,"z":6},7],"c":8}

methods

var stringify = require('fast-json-stable-stringify')

var str = stringify(obj, opts)

Return a deterministic stringified string str from the object obj.

options

cmp

If opts is given, you can supply an opts.cmp to have a custom comparison function for object keys. Your function opts.cmp is called with these parameters:

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:

var stringify = require('fast-json-stable-stringify');

var obj = { c: 8, b: [{z:6,y:5,x:4},7], a: 3 };
var s = stringify(obj, function (a, b) {
    return a.key < b.key ? 1 : -1;
});
console.log(s);

which results in the output string:

{"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:

var stringify = require('fast-json-stable-stringify');

var obj = { d: 6, c: 5, b: [{z:3,y:2,x:1},9], a: 10 };
var s = stringify(obj, function (a, b) {
    return a.value < b.value ? 1 : -1;
});
console.log(s);

which outputs:

{"d":6,"c":5,"b":[{"z":3,"y":2,"x":1},9],"a":10}

cycles

Pass true in opts.cycles to stringify circular property as __cycle__ - the result will not be a valid JSON string in this case.

TypeError will be thrown in case of circular object without this option.

install

With npm do:

npm install fast-json-stable-stringify

benchmark

To run benchmark (requires Node.js 6+):

node benchmark

Results:

fast-json-stable-stringify x 17,189 ops/sec ±1.43% (83 runs sampled)
json-stable-stringify x 13,634 ops/sec ±1.39% (85 runs sampled)
fast-stable-stringify x 20,212 ops/sec ±1.20% (84 runs sampled)
faster-stable-stringify x 15,549 ops/sec ±1.12% (84 runs sampled)
The fastest is fast-stable-stringify

license

MIT