Deep clone an object

deepClone.js

/**
 * @type {Function}
 */
var toString = Object.prototype.toString;

/**
 * @description Clones an object using deep copy
 * 
 * @param {Object} sourceObject Object to clone
 * @returns {Object}  Cloned object.
 * @throws {Error}
 */
function deepClone(sourceObject) {

    if (!sourceObject || typeof sourceObject != "object") {
        // Any non-object (Boolean, String, Number), null, undefined, NaN
        return sourceObject;
    }

    // Honor native/custom clone methods
    if (sourceObject.clone && toString.call(sourceObject.clone) == "[object Function]") {
        return sourceObject.clone(deep);
    }

    // Date
    if (sourceObject instanceof Date) {
        var clone = new Date();
        clone.setTime(sourceObject.getTime());
        return clone;
    }

    // Array
    if (sourceObject instanceof Array) {
        var clone = [];
        for (var i = 0, len = sourceObject.length; i < len; i++) {
            clone[i] = deepClone(sourceObject[i]);
        }
        return clone;
    }

    // RegExp
    if (toString.call(sourceObject) == "[object RegExp]") {
        return new RegExp(sourceObject);
    }
    
    // DOM elements
    if (sourceObject.nodeType && toString.call(sourceObject.cloneNode) == "[object Function]") {
        // Deep clone the node
        return sourceObject.cloneNode(true);
    }

    if (sourceObject instanceof Object) {
        var clone = {};
        for (var key in sourceObject) {
            if (sourceObject.hasOwnProperty(key)) clone[key] = deepClone(sourceObject[key]);
        }
        return clone;
    }
    throw new Error("Unable to clone this object.");
}

if (typeof module === 'object' && module.exports) {
    module.exports = deepClone
}

test.js

/* global describe, it */
var assert = require('assert');
var deepClone = require('./deepClone');

describe('deepClone', function() {
    
    var testObj;
    var clonedObj;

    before( function() {
        testObj = {
            a: 2,
            b: {
                c: "A Name",
                d: function(param) {
                    return param
                },
                e: {
                    f: 4,
                    g: 67,
                    h: [2, 6, Number]
                },
                g: false
            },
            j: new Date(),
            k: /^[0-9]/
        };
    });

    beforeEach( function() {
        clonedObj = deepClone(testObj);
    });

    it('should clone testObj', function() {
        assert.deepEqual(testObj, clonedObj);
    });

    it('should not be \'equal\'', function() {
        clonedObj.a = 3;
        assert.notDeepEqual(testObj, clonedObj);
    });

    it('should not be \'equal\'', function() {
        clonedObj.b.g = true;
        assert.notDeepEqual(testObj, clonedObj);
    });

    it('should not be \'equal\'', function() {
        clonedObj.b.e.h[0] = 1;
        assert.notDeepEqual(testObj, clonedObj);
    });

});

Usage

var deepClone = require('./js-clone/index.js');

var object = {
    name: 'Kator James',
    work: {
        companyName: 'LogicalAddress Ltd',
        getCompanyName: function() {
            // ...
        }
    }
}
var clone = deepClone(object);

Test

# To run unit tests
npm install --save-dev mocha
node_modules/mocha/bin/_mocha test.js
# To run test with coverage
npm install --save-dev mocha istanbul standard
istanbul cover node_modules/mocha/bin/_mocha test.js --bail