[翻译]High Performance JavaScript(003)
Dynamic Script Elements 动态脚本元素
The Document Object Model (DOM) allows you to dynamically create almost any part of an HTML document using JavaScript. At its root, the <script> element isn't any different than any other element on a page: references can be retrieved through the DOM, and they can be moved, removed from the document, and even created. A new <script> element can be created very easily using standard DOM methods:
文档对象模型（DOM）允许你使用JavaScript动态创建HTML的几乎全部文档内容。其根本在于，<script>元素与页面其他元素没有什么不同：引用变量可以通过DOM进行检索，可以从文档中移动、删除，也可以被创建。一个新的<script>元素可以非常容易地通过标准DOM函数创建：
var script = document.createElement_x("script");
script.type = "text/javascript";
script.src = "file1.js";
document.getElementsByTagName("head")[0].appendChild(script);
This new <script> element loads the source file file1.js. The file begins downloading as soon as the element is added to the page. The important thing about this technique is that the file is downloaded and executed without blocking other page processes, regardless of where the download is initiated. You can even place this code in the <head> of a document without affecting the rest of the page (aside from the one HTTP connection that is used to download the file).
新的<script>元素加载file1.js源文件。此文件当元素添加到页面之后立刻开始下载。此技术的重点在于：无论在何处启动下载，文件的下载和运行都不会阻塞其他页面处理过程。你甚至可以将这些代码放在<head>部分而不会对其余部分的页面代码造成影响（除了用于下载文件的HTTP连接）。
When a file is downloaded using a dynamic script node, the retrieved code is typically executed immediately (except in Firefox and Opera, which will wait until any previous dynamic script nodes have executed). This works well when the script is self-executing but
相关文档：
javascript中event.keycode
keycode 8 = BackSpace BackSpace
keycode 9 = Tab Tab
keycode 12 = Clear
keycode 13 = Enter
keycode 16 = Shift_L
keycode 17 = Control_L
keycode 18 = Alt_L
keycode 19 = Pause
keycode 20 = Caps_Lock
keycode 27 = Escape Escape
keycode 32 = space space ......
看书的时候遇到这样一个问题，程序代码如下
var ob = function(){
var obj = this;
function fn1(){
alert( obj === window );//false
alert( this === window );//ture
}
this.fn2 = function() {
fn1();
}
}
当时很不明白fn1里面第二个alert的结果，为 ......
自定义一个log函数,输出传入函数的对象或者信息.
Log.js
// JScript source code
function
log(category, message, object) {
// If this category is explicitly disabled, do nothing
if
(log.options[category + "Disabled
"]) return
;
// Find the container
var
id = categ ......
<html>
<body>
<script type="text/javascript">
//方法一
var num_arr= [];
for (var i = 0 ; i < 10 ; i ++)
{
num_arr[i] = i;
}
document.write(num_arr+'</br>');
//方法二
var obj_arr=new Array();
obj_arr[6]='ss';
document.write(obj_arr.len ......
