到现在为止，本章讨论的数组都只包含基本数据类型的元素，比如数字和字符串。数组还
可以包含对象，数组的方法和属性对对象依然适用。
请看下面的例子：
function Point(x,y) {
this.x = x;
this.y = y;
}
function displayPts(arr) {
for (var i = 0; i < arr.length; ++i) {
print(arr[i].x + ", " + arr[i].y);
}
}
var p1 = new Point(1,2);
var p2 = new Point(3,5);
var p3 = new Point(2,8);
var p4 = new Point(4,4);
var points = [p1,p2,p3,p4];
for (var i = 0; i < points.length; ++i) {
console.log("Point " + parseInt(i+1) + ": " + points[i].x + ", " + points[i].y);
}
var p5 = new Point(12,-3);
points.push(p5);
print("After push: ");
displayPts(points);
points.shift();
print("After shift: ");
displayPts(points);
这段程序的输出为：
Point 1: 1, 2
Point 2: 3, 5
Point 3: 2, 8
Point 4: 4, 4
After push:
1, 2
3, 5
2, 8
4, 4
12, -3
After shift:
3, 5
2, 8
4, 4
12, -3
使用push() 方法将点(12, -3) 添加进数组，使用shift() 方法将点(1, 2) 从数组中移除。
