Javascript is the mainstream programming language for Web application clients. In actual projects, you often need to dynamically add JavaScript code to ASP. NET webpages.
1. Add JavaScript code directly in the control declaration
<Asp: button id = "button2" runat = "server" onmouseover = "this. style. color = 'red' "onmouseout =" this. style. color = 'black' "text =" color-changing buttons "/>
Onmouseover and onmouseout are not the attributes of the button control, but the event attributes of the HTML element. When an HTML page is displayed, ASP. NET will uncertain send the attributes that cannot be parsed to the browser client.
2. Use the control. Attributes. Add method to add JavaScript code
<SCRIPT type = "text/JavaScript">
// Implement the JavaScript function of the character counter
Function inputcounter (inputid, counterid, maxlength)
{
VaR TXT = Document. getelementbyid (inputid );
VaR counterid = Document. getelementbyid (counterid );
If (txt! = NULL) & (counterid! = NULL ))
{
Counterid. value = (parseint (maxlength)-TXT. value. Length). tostring ();
}
}
</SCRIPT>
Protected void page_load (Object sender, eventargs E)
{
// Dynamically "Assemble" JavaScript scripts,
// Inputcounter () is a JavaScript function defined in the String script = "inputcounter ('{0}', '{1}', {2 });";
Script = string. Format (script, txtinput. clientid, txtcount. clientid, 2000 );
// Append the Javascript script to the properties of the text box control.
Txtinput. Attributes. Add ("onkeyup", script );
}
3. Use registerstartupscript and other methods
The page class provides a clientscript object, which has a series of methods to dynamically inject Javascript code into ASP. NET pages.
<Input id = "htmlbutton1" type = "button" runat = "server" value = "I am a common HTML button, and now there is no response code"/>
<HR/>
<Asp: button id = "btnregisterjavascript" runat = "server" text = "dynamic JavaScript code injection to webpages"
Onclick = "btnregisterjavascript_click"/>
Protected void btnregisterjavascript_click (Object sender, eventargs E)
{
// JavaScript code block to be added
String script = "function sayhello () {alert (\" Hello \");}";
// Any of the following two sentences can add JavaScript code blocks to the page
// Identify the differences between the two methods through the generated HTML webpage source code
// Clientscript. registerclientscriptblock (this. GetType (), "sayhello", script, true );
Clientscript. registerstartupscript (this. GetType (), "sayhello", script, true );
Htmlbutton1.value = "I am a common HTML button, and now the response code is dynamically mounted ";
// Add an event response function to the button
Htmlbutton1.attributes ["onclick"] = "sayhello ();";
}
3.1 differences between registerclientscriptblock and registerstartupscrip
The two methods have different code positions in the client: the JavaScript code added by registerclientscriptblock appears inside the <body> element of the page, which is often mixed with other HTML code, therefore, these codes may not be able to access all HTML elements on the page. The javascript code added by registerstartupscript appears at the end of the <body> element.
This article mainly references Mr. Jin xuliang's ASP. NET Programming Tutorial.
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
