SOURCE

var clone = function (obj) {
    if(obj == undefined || obj == null || obj == '') return;
    var cloneObj = {};
    if (obj instanceof Array) {
        cloneObj = obj.concat();
    } else {
        for (var i in obj) {
            var property = obj[i];
            if (property instanceof Object
                && !property instanceof Array) {
                cloneObj[i] = clone(property);
            } else {
                cloneObj[i] = property;
            }
        }
    }
    return cloneObj;
}

var b = {
    num: 1111,
    name: "jack",
    gender: 'male',
    address: [{ a: 'a' }, { b: 'b' }, { c: 'c' }],
    file: {
        name: 'test.txt',
        a: {
            b: {
                c: {
                    d: "fjiewjgiew"
                }
            }
        }
    }
}

var a = [1, 2, 3];

var aclone = clone();

console.log(a);
console.log(aclone);
console.log(a === aclone)