What's the difference

1

In terms of performance and/or best practices, is there any difference between these three?

var arr:Array = new Array();
arr = [1, 3, 8, 9];
...or...
var arr:Array = new Array(4);
arr = [1, 3, 8, 9];
...or...
var arr:Array;
arr = [1, 3, 8 9]