ASP.NET2.0中Page.ClientScript.RegisterClientScriptBlock与RegisterClientScriptBlock
最近的项目用到这样一段代码:
//要根据后台取的值初始化页面显示
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
GetGovShiftSetInfo();//此方法作用：取数据库数据来设置rbTwo状态
if (rbTwo.Checked)
{
//Page.RegisterStartupScript("", "<script>istwo();</script>"); //1.0的语法构造，已过时
Page.ClientScript.RegisterStartupScript(this.GetType(), "MyScript", "istwo();", true);
}
}
}
----------------------------------------------------------------------------------------
//放在前台的JS：
<script type="text/javascript">
function istwo()
{
var obj1=window.document.getElementById("ctl00_MainContent_panelPmB");
var obj2=window.document.getElementById("ctl00_MainContent_panelPmE");
var obj3=window.document.getElementById("ctl00_MainContent_lbAmB");
var obj4=window.document.getElementById("ctl00_MainContent_lbAmE");
var obj5=window.document.getElementById("ctl00_MainContent_panelCard");
obj1.style.visibility = "hidden";
obj2.style.visibility = "hidden";
obj3.style.visibility = "hidden";
obj4.style.visibility = "hidden";
obj5.style.visibility = "hidden";
var no3= parseInt(window.document.getElementById("ctl00_MainContent_txtValue").value);
if (no3 < 5 || no3 > 500 )
{
alert("上下班刷卡有效时限：[5-500]分钟内");
window.document.getElementById("ctl00_MainContent_rbFour").focus();
window.document.getElementById("ctl00_MainContent_rbFour").checked=true;
isfour();
}
}
--------------------------------------------------------------------------------------------------------
之所以没用Page.ClientScript.RegisterClientScriptBlock而用Page.ClientScript.RegisterStartupScript是因为：RegisterStartupScript 把script放置在ASP.NET page的底部，而RegisterClientScriptBlock把script放置在ASP.NET page的顶部，用RegisterClientScriptBlock会报错:javascript函数不到对象
1.使用 Page.ClientScript.RegisterClientScriptBlock
Listing 4-10: Using the RegisterClientScriptBlock method
c#
<%@ Page Language=”C#” %>
<script runat=”server”>
protectedvoid Page_Load(object sender, EventArgs e)
{
string myScript = @”function AlertHello() { alert(‘Hello ASP.NET’); }”;
Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
“MyScript”, myScript, true);
}
</script>
运行结果如下：
<html xmlns=”http://www.w3.org/1999/xhtml” >
<head><title>
Adding JavaScript
</title></head>
<body>
<form method=”post” action=”JavaScriptPage.aspx” id=”form1”>
<div>
<input type=”hidden” name=”__VIEWSTATE”
value=”/wEPDwUKMTY3NzE5MjIyMGRkiyYSRMg+bcXi9DiawYlbxndiTDo=” />
</div>
<script type=”text/javascript”>
<!--
function AlertHello() { alert(‘Hello ASP.NET’); }// -->
</script>
<div>
<input type=”submit” name=”Button1” value=”Button” onclick=”AlertHello();”
id=”Button1” />
</div>
</form>
</body>
</html>
2.使用Page.ClientScript.RegisterStartupScript
RegisterStartupScript方法与RegisterClientScriptBlock方法最大的不同是：RegisterStartupScript 把script放置在ASP.NET page的底部，而RegisterClientScriptBlock把script放置在ASP.NET page的顶部
如果你的页面中有如下代码：
<asp:TextBox ID=”TextBox1” Runat=”server”>Hello ASP.NET</asp:TextBox>
Listing 4-11: Improperly using the RegisterClientScriptBlock method
c#
protectedvoid Page_Load(object sender, EventArgs e)
{
string myScript = @”alert(document.forms[0][‘TextBox1’].value);”;
Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
“MyScript”, myScript, true);
}
此页面运行时会报错，原因是JavaScript function先于text box被安放于浏览器。因此JavaScript function找不到TextBox1。
Listing 4-12: Using the RegisterStartupScript method
c#
protectedvoid Page_Load(object sender, EventArgs e)
{
string myScript = @”alert(document.forms[0][‘TextBox1’].value);”;
Page.ClientScript.RegisterStartupScript(this.GetType(),
“MyScript”, myScript, true);
}
这段代码把JavaScript function放置于ASP.NET page底部，因此JavaScript运行时它能找到TextBox1。
3.使用Page.ClientScript.RegisterClientScriptInclude
许多开发者把JavaScript放置在.js文件中，使用RegisterClientScriptInclude方法可以注册.js文件中的JavaScript。
Listing 4-13: Using the RegisterClientScriptInclude method
c#
string myScript = “myJavaScriptCode.js”
Page.ClientScript.RegisterClientScriptInclude(“myKey”, myScript);
这将在ASP.NET页面产生如下结构：
<script src=”myJavaScriptCode.js” type=”text/javascript”></script>
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