nano-copy/index.js

Superfast, super small JavaScript object deep copy.

(() => {
	const f = function() {},
		_Buffer = typeof(Buffer)==="function" ? Buffer : f,
		_Blob = typeof(Blob)==="function" ? Blob : f,
		_DataView = typeof(DataView)==="function" ? DataView : f,
		cloners = new Set([ArrayBuffer,BigInt,_Blob,Boolean,_Buffer,_DataView,Date,Error,Int8Array,Int16Array,Int32Array,Map,Number,RegExp,Set,String,Uint8Array,Uint16Array,Uint32Array]),
		directs = new Set([Boolean,Error,Number,Promise,String,Symbol,WeakMap,WeakSet]),
		nanoCopy = (data,options={},cloned=new WeakMap()) => {
			const type = typeof(data),
				{nonStandard,nonEnumerable} = options; // nonEnumerable not yet supported
			if(!data || type!=="object" || directs.has(data.constructor) || type==="function" || type==="undefined") {
				if(data && type==="object") cloned.set(data,data);
				return data;
			}
			let clone = cloned.get(data);
			if(clone) return clone;
			if(cloners.has(data.constructor)) {
				clone = data instanceof _Buffer
					? _Buffer.from(data)
					: data instanceof ArrayBuffer
						? data.slice(0)
						: data instanceof _Blob 
							? new _Blob([data],{type:data.type,endings:data.endings})
							: data instanceof _DataView
								? new _DataView(nanoCopy(data.buffer,options,cloned),data.byteOffset,data.byteLength)
								: new data.constructor(data);
				cloned.set(data,clone);
				if(clone instanceof Set || clone instanceof Map) {
					for(const [key,value] of [...clone.entries()]) {
						if(clone instanceof Set) {
							clone.delete(key);
							clone.add(nanoCopy(key,options,cloned));
						} else if(clone instanceof Map) {
							clone.delete(key);
							clone.set(nanoCopy(key,options,cloned),nanoCopy(value,options,cloned));
						}
					}
				}
				if(nonStandard) {
					for(const key in data) {
						if(isNaN(parseInt(key))) {
							clone[key] = data[key];
						}
					}
				}
			} else if(Array.isArray(data) && !nonStandard) {
				clone = data.map((item) => nanoCopy(item,options,cloned));
			} else {
				if(data.constructor && data.constructor.from && !Array.isArray(data)) {
					try {
						clone = data.constructor.from(data);
						return clone;
					} catch(error) {
						// ignore and try Object.create
					}
				}
				clone = Array.isArray(data) ? new data.constructor() : Object.create(Object.getPrototypeOf(data));
				cloned.set(data,clone);
				for(const key in data) {
					const value = data[key];
					clone[key] = nanoCopy(value,options,cloned);
				}
			}
			return clone;
		}
	if(typeof(module)!=="undefined") {
		module.exports = nanoCopy;
		nanoCopy.nanoCopy = nanoCopy;
	}
	if(typeof(globalThis)!=="undefined") {
		globalThis.nanoCopy = nanoCopy;
	}
})();