[翻译]High Performance JavaScript(023)
Data Formats 数据格式
When considering data transmission techniques, you must take into account several factors: feature set, compatibility, performance, and direction (to or from the server). When considering data formats, the only scale you need for comparison is speed.
在考虑数据传输技术时，你必须考虑这些因素：功能集，兼容性，性能，和方向（发给服务器或者从服务器接收）。在考虑数据格式时，唯一需要比较的尺度的就是速度。
There isn't one data format that will always be better than the others. Depending on what data is being transferred and its intended use on the page, one might be faster to download, while another might be faster to parse. In this section, we create a widget for searching among users and implement it using each of the four major categories of data formats. This will require us to format a list of users on the server, pass it back to the browser, parse that list into a native JavaScript data structure, and search it for a given string. Each of the data formats will be compared based on the file size of the list, the speed of parsing it, and the ease with which it's formed on the server.
没有哪种数据格式会始终比其他格式更好。根据传送什么数据、用于页面上什么目的，某种格式可能下载更快，另一种格式可能解析更快。在本节中，我们创建了一个窗口小部件用于搜索用户信息并用四种主流的数据格式实现它。这要求我们在服务器端格式化一个用户列表，将它返回给浏览器，将列表解析成JavaScript数据格式，并搜索特定的字符串。每种数据格式将比较列表的文件大小，解析速度，和服务器上构造它们的难易程度。
XML
When Ajax first became popular, XML was the data format of choice. It had many things going for it: extreme interoperability (with excellent support on both the server side and the client side), strict formatting, and easy validation. JSON hadn't been formalized yet as an interchange format, and almost every language used on servers had a library available for working with XML.
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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;
......
第五章 Strings and Regular Expressions 字符串和正则表达式
Practically all JavaScript programs are intimately tied to strings. For example, many applications use Ajax to fetch strings from a server, convert those strings into more easily usable JavaScript objects, and ......
Yielding with Timers 用定时器让出时间片
Despite your best efforts, there will be times when a JavaScript task cannot be completed in 100 milliseconds or less because of its complexity. In these cases, it's ideal to yield control of the UI thread so that UI updates may occur ......
Splitting Up Tasks 分解任务
What we typically think of as one task can often be broken down into a series of subtasks. If a single function is taking too long to execute, check to see whether it can be broken down into a series of smaller functions that complete in smaller ......
