js中定义数组的方式
 一.   var  aColors = new Array;
                   aColors[0] = 'red'; 
                   aColors[1] = 'green';
                   aColors[2] = 'blue';
 
    二.  var aColors = new Array('red','green','blue');
 
    三.  var aColors = ["red","green","blue"];