Quick Deep Clone (qdclone)

Quick deep cloning for JavaScript.

Unsafe for use on cyclical data structures. Does not copy functions as object properties.

Usage

Pass an object to clone as the first argument.
Pass true as the second argument to construct prototypes, empty or false to instantiate as plain objects.

Performance comes at a cost:

no cyclic objects
no protos that require arguments on construction (if cast flag is true)
no objects that shadow global proto properties
no polluted base prototypes

clone(obj, cast = false)

Example

const qdclone = require('quick-deep-clone');

let x = {
	str: 'str',
	num: 10,
	arr: [0, 1, 2]
};

function A() {
	this.str = 'str';
	this.num = 10;
	this.arr = [0, 1, 2];
}

// deep clone a plain object
console.log(qdclone(x));

// deep clone a prototyped object
console.log(qdclone(new A(), true));

// deep clone a prototyped object as a plain object
console.log(qdclone(new A(), false));

Benchmarks

Package	Time (ms)
deep-clone@3.0.3	1361
rfdc@1.1.4	1048
qdclone	441
qdclone (* with casting)	525

* only quick-deep-clone supports casting prototypes

const { performance } = require('perf_hooks');

const cloners = {
	'deep-clone': require('deep-clone'),
	'rfdc': require('rfdc')(),
	'qdclone': require('quick-deep-clone')
};

const ITERATIONS = 10000;

setImmediate(() => {

	let x = makeX();
	
	console.log('\nRunning...\n')

	runBench('deep-clone', x, ITERATIONS);
	runBench('rfdc', x, ITERATIONS);
	runBench('qdclone', x, ITERATIONS);
	
	console.log('Running with prototype casting (only supported by qdclone)...\n');

	runBench('qdclone', x, ITERATIONS, true);
});

function runBench(type, obj, iterations, ...args) {
	
	let cloned;

	console.log(`Clone via ${type}...`);
	
	let benchStart = performance.now();

	for (let i = 0; i < iterations; ++i) {
		cloned = cloners[type](obj, ...args);
	}

	console.log(`${performance.now() - benchStart} ms\n`);

	return cloned;
}

function makeX() {

	let x = {
		str: 'str',
		num: 10,
		arr: [0, 1, 2],
		date: new Date(),
		bool: false,
		sub: {
			str2: 'abcdefghijklmnopqrstuvwxyz',
			num2: 9999999.9999999,
			bool2: true,
			arr2: [-.0000001, true, 'asdf', 100000.00001, [1, 2, 3], 'loooooooooooong']
		}
	};

	let x2 = {
		x: JSON.parse(JSON.stringify(x))
	};

	let x3 = {
		x: JSON.parse(JSON.stringify(x)),
		x2: JSON.parse(JSON.stringify(x2))
	};

	let xs = [];

	for (let i = 0; i < 100; ++i) {
		xs.push(JSON.parse(JSON.stringify(x)));
	}

	return new class X {
		constructor() {
			this.x = x;
			this.x2 = x2;
			this.x3 = x3;
			this.xs = xs;
		}
	}
}

Contributing

Feel free to make changes and submit pull requests whenever.

License

Mousetouch uses the MIT license.

obsius / quick-deep-clone