JavaScript中定義數組

1.先定義再賦值

var myArray1 = new Array();   //不定義元素個數
     myArray1[0] = "第";
     myArray1[1] = "一";
     myArray1[2] = "種";
var myArray2 = new Array(3);   //定義元素的個數
     myArray2[0] = "第";
     myArray2[1] = "二";
     myArray2[2] = "種";

　　

 2.定義數組時同時賦值

var　myArray3 = new Array("第","三","種");
//你需要在數組內指定數值或者邏輯值，那么變量類型應該是數值變量或者布爾變量，而不是字符變量
var myArray4 = [
			{"num":"1001","name":"jack","age":16},
			{"num":"1002","name":"Mary","age":17},
			{"num":"1003","name":"Tom","age":19}
			];
//注意中括號和大括號的位置

　

 3. 注意

   · 數組只有數組長度一個屬性

   · 如果沒有給數組賦值得到的是undefined，打印是”“

   · 數組長度不夠可以自動擴充，不存在越界的問題