Question

I have two arrays

arr1 = new Array();
arr2 = new Array();

If i do the following:

arr1 = arr2;

in javascript is this assigning by value or by reference? What i mean is, after doing the above, will further changes in arr2 affect arr1’s content and also the other way around?

Answer 1

Here is a clone function I wrote…

            /**
         * Clone an Object or Array.
         * 
         * @param {Object}
         *          obj the Object or Array that should be cloned
         * @param {Boolean}
         *          deep if true also clones the elements of an Object or Array,
         *          default is true
         * @return
         * @type Object
         */
        function cloneObject(obj, deep) {
            try {
                deep = !deep ? false : true;
                if (obj.constructor === Object) {
                    var nObj = {}, elem = null;
                    for (elem in obj) {
                        if (obj.hasOwnProperty(elem)) {
                            nObj[elem] = deep ? cloneObject(obj[elem]) : obj[elem];
                        }
                    }
                    return nObj;
                }
                if (obj.constructor === Array) {
                    var nArr = [], i = 0;
                    for (i = 0; i < obj.length; i++) {
                        nArr[i] = deep ? cloneObject(obj[i]) : obj[i];
                    }
                    return nArr;
                }
            } catch (e) {
                console.error("cloneObject(", arguments, ") >", e);
            }
            return obj;
        };