JavaScript基础知识1
Javascript数据类型
由于javascript是弱类型语言，即定义变量时不必声明其类型
。但这并不意味着变量没有类型。因为赋值时会自动匹配数据类型！
目前用到的基本数据类型
number
boolean
string
var i
i="test";//这时i就成了string类型
var i
i=4;//这时i就成了number类型
常用对象类型<object>
Date
Number
Boolean
String
RegExp
Array
Object
以上对象类型的用法
var i;
i=new Number(123);
i.toString(2);//转为2进制。8为8进制
再如：
var i
i=new Array(1,2,3);
相关文档：
<script>setTimeout("redirect('<?=$url_forward?>');", <?=$ms?>);</script>
设置分页：$page $pagesize $offset = ($page-1)*$pagesize;
$limit = "limit $offset,$pagesize" ......
Identifier Resolution Performance 标识符识别性能
Identifier resolution isn't free, as in fact no computer operation really is without some sort of performance overhead. The deeper into the execution context's scope chain an identifier exists, the slower it is to access for ......
Nested Members 嵌套成员
Since object members may contain other members, it's not uncommon to see patterns such as window.location.href in JavaScript code. These nested members cause the JavaScript engine to go through the object member resolution process each time a dot is ......
第三章 DOM Scripting DOM编程
DOM scripting is expensive, and it's a common performance bottleneck in rich web applications. This chapter discusses the areas of DOM scripting that can have a negative effect on an application's responsiveness and gives recommendations o ......
2、原型方式写类，原型方式继承
core js自身的对象系统就是采用原型方式(prototype based)继承的。或者说core
js没有采用常见的类继承(class
based)系统，而是使用原型继承来实现自己的对象系统。工作中我们也可以用原型方式来实现继承，代码复用以构建自己的功能模块。
/**
* 父类Polygon:多边形
*
*/
functio ......
