JavaScript中定义数组

1.先定义再赋值

var myArray1 = new Array();   //不定义元素个数
     myArray1[0] = "第";
     myArray1[1] = "一";
     myArray1[2] = "种";
var myArray2 = new Array(3);   //定义元素的个数
     myArray2[0] = "第";
     myArray2[1] = "二";
     myArray2[2] = "种";

　　

 2.定义数组时同时赋值

var　myArray3 = new Array("第","三","种");
//你需要在数组内指定数值或者逻辑值，那么变量类型应该是数值变量或者布尔变量，而不是字符变量
var myArray4 = [
			{"num":"1001","name":"jack","age":16},
			{"num":"1002","name":"Mary","age":17},
			{"num":"1003","name":"Tom","age":19}
			];
//注意中括号和大括号的位置

　

 3. 注意

   · 数组只有数组长度一个属性

   · 如果没有给数组赋值得到的是undefined，打印是”“

   · 数组长度不够可以自动扩充，不存在越界的问题