| 如果是这种情况的话，我们定义的PleaseWait()函数会加在已经存在的onclick代码的最后面，紧跟在客户端检查的boolin变量Page_IsValid后面。这个变量代表是否使用了验证控件。如果Page_IsValid的值是false，"Please wait"信息将不显示。如果为True则显示。
private string ModifyJavaScriptOnClick(string sHtml)
{
// Thanks to CodeProject member KJELLSJ (Kjell-Sverre Jerijaervi)
// for code ideas to allow the button to work with client-side validation
string sReturn = "";
string sPleaseWaitCode = GeneratePleaseWaitJavascript();
// is there an existing onclick attribute?
Regex rOnclick = new Regex("onclick=\"(?<onclick>[^\"]*)");
Match mOnclick = rOnclick.Match(sHtml);
if (mOnclick.Success)
{
// there is an existing onclick attribute;
// add our code to the end of it; if client-side
// validation has been rendered, make sure
// we check to see if the page is valid;
string sExisting = mOnclick.Groups["onclick"].Value;
string sReplace = sExisting
+ (sExisting.Trim().EndsWith(";") ? "" : "; ");
if (IsValidatorIncludeScript() && this.CausesValidation)
{
// include code to check if the page is valid
string sCode = "if (Page_IsValid) " + sPleaseWaitCode
+ " return Page_IsValid;";
// add our code to the end of the existing onclick code;
sReplace = sReplace + sCode;
}
else
{
// don''t worry about the page being valid;
sReplace = sReplace + sPleaseWaitCode;
}
// now substitute our onclick code
sReplace = "onclick=\"" + sReplace;
sReturn = rOnclick.Replace(sHtml, sReplace);
}
else
{
// there isn''t an existing onclick attribute;
// add ours
int i = sHtml.Trim().Length - 2;
string sInsert = " onclick=\"" + sPleaseWaitCode + "\" ";
sReturn = sHtml.Insert(i, sInsert);
}
return sReturn;
}
这个IsValidatorIncludeScript() 利用上面的检查来查看是否有使用页面注册的asp.net验证控件的标准Javascript代码块。下面则用一个简单的方法测试了是否有验证代码和像Page_IsValid的变量存在。
private bool IsValidatorIncludeScript()
{
// return TRUE if this page has registered javascript
// for client-side validation; this code may not be registered
// if ASP.NET detects what it thinks (correctly or incorrectly)
// is a down-level browser.
return this.Page.IsStartupScriptRegistered("ValidatorIncludeScript");
}
下面这个GeneratePleaseWaitJavascript()构建了包含在onclick属性中的PleaseWait() Javascript函数。我们可以通过检查控件的属性来决定想要的布局。
private string GeneratePleaseWaitJavascript()
{
// create a JavaScript "PleaseWait()" func
|
