易截截图软件、单文件、免安装、纯绿色、仅160KB

JavaScript编程笔记

新中……
1、数据类型验证问题
  Asp.Net虽然有验证控件,但是有些复杂的验证还是得传到服务器上进行,用js速度和性能都比较好
<script>
 //检查是否为任意数(实数)
function isNumeric(strNumber) {
var newPar=/^(-|\+)?\d+(\.\d+)?$/
alert(newPar.test(strNumber)); }
 //检查是否为正数
function isUnsignedNumeric(strNumber) {
var newPar=/^\d+(\.\d+)?$/
alert(newPar.test(strNumber)); }
//检查是否为整数
function isInteger(strInteger) {
var newPar=/^(-|\+)?\d+$/
alert(newPar.test(strInteger)); }
//检查是否为正整数
function isUnsignedInteger(strInteger) {
var newPar=/^\d+$/
alert(newPar.test(strInteger)); }
</script>
2、asp.net中用alert()实现换行问题
     asp.net中用response.Write("<script>alert('提示:\n操作出错!');</script>");无法执行。
     将字符串写成
     say="提示:\\n操作出错!"
     say=@"提示:\n操作出错!"
  
 3、js实现刷新验证码
     单击图片刷新:
<img id="CheckImg" src="CreatImage.aspx" onclick="this.src='CreatImage.aspx?temp='+Math.random()"/>
     单击“刷新验证码”按钮刷新
    function imagechick()
   {
     form1.CheckImg.src="CreatImage.aspx?temp="+Math.random();
     return false;//不上传到服务器
   }
     其中CreatImage.aspx为产生验证码图片的页面,源码见:C#产生图形验证码
4、js中使用正则表达式的方法
    格式是:/正则表达式/
    必须用两个斜杠把正则表达式括起来。
   如非法字符检测正则表达式为:^(?:[\u4e00-\u9fa5]*\w*\s*)+$
   使用的代码为:
      var newPar=/^(?:[\u4e00-\u9fa5]*\w*\s*)+$/;
      if(newPar.test("1234&1238*_~"))
      {
         &


相关文档:

[翻译]High Performance JavaScript(012)

第四章  Algorithms and Flow Control  算法和流程控制
    The overall structure of your code is one of the main determinants as to how fast it will execute. Having a very small amount of code doesn't necessarily mean that it will run quickly, and having a large amount of code ......

[翻译]High Performance JavaScript(013)

Conditionals  条件表达式
    Similar in nature to loops, conditionals determine how execution flows through JavaScript. The traditional argument of whether to use if-else statements or a switch statement applies to JavaScript just as it does to other languages. Since different b ......

[翻译]High Performance JavaScript(020)

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 ......

[翻译]High Performance JavaScript(026)

Use the Fast Parts  使用速度快的部分
    Even though JavaScript is often blamed for being slow, there are parts of the language that are incredibly fast. This should come as no surprise, since JavaScript engines are built in lower-level languages and are therefore compiled. Thou ......

[翻译]High Performance JavaScript(032)

Fiddler
    Fiddler is an HTTP debugging proxy that examines the assets coming over the wire and helps identify any loading bottlenecks. Created by Eric Lawrence, this is a general purpose network analysis tool for Windows that provides detailed reports on any browser or web request. ......
© 2009 ej38.com All Rights Reserved. 关于E健网联系我们 | 站点地图 | 赣ICP备09004571号