[翻译]High Performance JavaScript(019)
第六章 Responsive Interfaces 响应接口
There's nothing more frustrating than clicking something on a web page and having nothing happen. This problem goes back to the origin of transactional web applications and resulted in the now-ubiquitous "please click only once" message that accompanies most form submissions. A user's natural inclination is to repeat any action that doesn't result in an obvious change, and so ensuring responsiveness in web applications is an important performance concern.
没有什么比点击页面上的东西却什么也没发生更令人感到挫折了。这个问题又回到了原始网页交互程序和现在已无处不在的提交表单时弹出的“请勿重复提交”消息上面。用户自然倾向于重复尝试这些不发生明显变化的动作，所以确保网页应用程序的响应速度也是一个重要的性能关注点。
Chapter 1 introduced the browser UI thread concept. As a recap, most browsers have a single process that is shared between JavaScript execution and user interface updates. Only one of these operations can be performed at a time, meaning that the user interface cannot respond to input while JavaScript code is executed and vice versa. The user interface effectively becomes "locked" when JavaScript is executing; managing how long your JavaScript takes to execute is important to the perceived performance of a web application.
第一节介绍了浏览器UI线程概念。总的来说，大多数浏览器有一个单独的处理进程，它由两个任务所共享：JavaScript任务和用户界面更新任务。每个时刻只有其中的一个操作得以执行，也就是说当JavaScript代码运行时用户界面不能对输入产生反应，反之亦然。或者说，当JavaScript运行时，用户界面就被“锁定”了。管理好JavaScript运行时间对网页应用的性能很重要。
The Browser UI Thread 浏览器UI线程
The process shared by JavaScript and user interface updates is frequently referred to as the browser UI thread (though the term "thread" is not necessarily accurate for all browsers). The UI thread works on a sim
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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 ......
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> ......
隐藏成员变量
在函数体内定义的变量为局部变量，离开函数就挂掉了
在函数体内使用this.成员变量名，则为window对象级变量，即全局变量
故需要这样隐藏成员变量，向外只暴露get、set函数
function testClass(name){
var _firstname=name;
return {
getname : function() {
return _fir ......
常规的方法是将年月日取出，然后分别判断范围，然后就判断闰年2月的天数
可以通过new Date(string)的构造，比较年月日字符是否发生变化判断。
function CheckDate(text) {
if (!text) return false;
text = text.replace(/[\/-]0?/g, "/");
if (!text.match(/^\d{4}\/\d{1,2}\/\d{1,2}$/)) return true;
......
A Note on Benchmarking 测试基准说明
Because a regex's performance can be wildly different depending on the text it's applied to, there's no straightforward way to benchmark regexes against each other. For the best result, you need to benchmark your regexes on test strings o ......
