Ways of defining an Array in Javascript

There are many ways of defining an Arrays in Javascript:-

1). var employee1 = new Array(3); 
    employee1[0] = "Vishal";
    employee1[1] = "Kumar";
    employee1[2] = "Neeraj";

2). var employee12  = ['Pune','Nagpur','Kanpur'];

3). var employee3 = [];    
    employee3.length = 3;
    employee3[0] = "Dot Net";

4). var employee4 = [,,,,]; //This will initialize the length property to 4.
    employee4[0] = "Vishal"; //Output will be Vishal,,,