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How do I use the aspx page to load a JavaScript function on a button click

Posted on 2008-10-24
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Last Modified: 2012-05-05
I need to load a JavaScript function upon a button click.  I forgot how do I relate the asp control inside the aspx page with the JavaScript and the OnClick event.

Could someone please send me this?

thans,
newbieweb
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Question by:newbieweb
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12 Comments
 
LVL 10

Accepted Solution

by:
jinn_hnnl earned 300 total points
ID: 22798435
<asp:Button ID="btAdd" runat="server" Text="Add" />

code behind Page_load
btAdd.Attributes.Add["onclick", "myJavaScriptFunction()");

Is that what you want ?

JINN
0
 
LVL 10

Expert Comment

by:jinn_hnnl
ID: 22798474
And maybe you wondered, this is how you register a javascript function which at server side you want to generate and render to your page

Hope this helps
JINN



public void Page_Load(Object sender, EventArgs e)
 {
    if(Request.QueryString["redirect"] != null)
      if(Request.QueryString["redirect"] == "true")
        if (!this.IsStartupScriptRegistered("Startup"))
        {
          // Form the script to be registered at client side.
          String scriptString = "<script language=\>";
          scriptString += "function MyFunction(){alert('hello world'}";     
          scriptString += "</script>";
          this.RegisterStartupScript("Startup", scriptString);
        }
 
       btAdd.Attributes.Add("onclick", "MyFunction()");   
 }

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LVL 10

Expert Comment

by:jinn_hnnl
ID: 22798479
ahh, forget about line 3 and 4 (i copied it from my other solution and forget to take it off)
JINN
0
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Author Comment

by:newbieweb
ID: 22798502
I was thinking more like this.  Except this does not work.  Is it the javaScript
of the ASP.NET that's at fault?

thanks,
newbieweb

<head runat="server">
    <title>Untitled Page</title>
    <script type="text/javascript">
        function DODataLookup(){
            window.location = "../DataLookup.aspx";
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="submitBtn" runat="server" script="DODataLookup()" Style="z-index: 100;
            left: 118px; position: absolute; top: 140px" Text="Submit" />
   
    </div>
    </form>
</body>
0
 
LVL 10

Expert Comment

by:jinn_hnnl
ID: 22798592
Oke then it should be:
 
<asp:Button ID="submitBtn" runat="server" OnClientClick="DODataLookup()" Style="z-index: 100; left: 118px; position: absolute; top: 140px" Text="Submit" />
   
Check this link
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx

JINN

^^

0
 
LVL 10

Expert Comment

by:jinn_hnnl
ID: 22798618
anyway you can set style like that for your button I guess, you will have to set the CssClass which refers to the predefine CSS class. If you want to simplify that:

<div style="z-index: 100; left: 118px; position: absolute; top: 140px">
     <asp:Button ID="submitBtn" runat="server" OnClientClick="DODataLookup()"  Text="Submit" />
</div>

or <span>

It is not possible to use normal html property for server control like you do with <input > <select ..> normal html element

JINN
0
 

Author Comment

by:newbieweb
ID: 22798860
This is not working.  Could it be the path name in the JavaScript?

how do I find the error?

newbieweb


<head runat="server">
    <title>Untitled Page</title>
    <script type="text/javascript">
        function DODataLookup(){
            window.location = "../DataLookup.aspx";
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div style="z-index: 100; left: 118px; position: absolute; top: 140px">
        <asp:Button ID="submitBtn" runat="server" OnClientClick="DODataLookup()"  Text="Submit" />
    </div>
    </form>
</body>
0
 
LVL 10

Expert Comment

by:jinn_hnnl
ID: 22799461
you can test if your button call the javascript by:

      function DODataLookup(){
           alert(' hey ');
            window.location = "../DataLookup.aspx";
    }

you see hey, then the next line is the problem, appear to me it will navigate to the parent folder of this page and lookfor datalookup.aspx ? is what you want? What you are doing is redirecting the current page to that page.

Play around with the path

Jinn
0
 
LVL 16

Assisted Solution

by:Gyanendra Singh
Gyanendra Singh earned 200 total points
ID: 22799472
I have test your code ... Its working in my end ... it seems that below line is not correct in your method

window.location = "../DataLookup.aspx";

please check the path  and correct it .. attached working code
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Untitled Page</title>
    <script type="text/javascript">
        function DODataLookup(){
        alert ( "HI")
            window.location = "../DataLookup.aspx";
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div style="z-index: 100; left: 118px; position: absolute; top: 140px">
        <asp:Button ID="submitBtn" runat="server" OnClientClick="DODataLookup()"  Text="Submit" />
    </div>
    </form>
</body>
</html>

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Author Comment

by:newbieweb
ID: 22801681
I'm having trouble with a null test in JavaScript for a var type:

        alert('OK1');
        var elem = document.getElementByID("recordLocatorTextBox");
       
        if (elem != 'undefined')
        {
               alert('OK2');
        }

what is the correct way to test if elem is null?  I never get OK2.

newbieweb
0
 
LVL 16

Expert Comment

by:sh0e
ID: 22801754
if(elem!=undefined)
0
 
LVL 10

Expert Comment

by:jinn_hnnl
ID: 22802609
There are major different between undefined and null,

If you check
 if (elem != null)
        {
               alert('OK2');
        }
it's the same as
 if(!elem),
and they are good enough

btw if you want to check if the property is set or not:
 if (elem.style != 'undefined') is the correct way (with quote)

Keep in mind, javascript is case sensitive:
var elem = document.getElementById("recordLocatorTextBox");
(instead of ID it's Id)

JINN
0

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