Register and execute a JavaScript function in a ASP.NET Page_Load event

Question

How can I register AND execute that JavaScript function in ASP.NET on a Page_Load event so my textbox content gets validated and if nothing is in there I can disable a save button?

function Validate(source, arguments)
{
}

Wouldn't a required field validator do this for you? Why use 'raw' javascript? — FiveTools
– FiveTools, Commented Jul 19, 2011 at 11:40
Do you mean that you want to execute a javascript, get a result and according it disable button and do all that on a Page_Load? — IUnknown
– IUnknown, Commented Jul 19, 2011 at 11:41
Why are you trying to do it with JavaScript? You're saying you want to perform this check in the Page_Load and disable the submit button, so the value of the TextBox is set by the code behind and not the user (otherwise you would check it with a RequiredFieldValidator or a CustomValidator), so why don't you perform the check directly in the code behind? — Albireo
– Albireo, Commented Jul 19, 2011 at 11:43
@Five The RequiredFieldValidator does only validate when something is entered and removed again. It should trigger on the page_load event! — msfanboy
– msfanboy, Commented Jul 19, 2011 at 11:45
If so - you can reference both your text box and save button in the page load event. If the text box text = string.empty disable your button. You could use the registerstartupscript below - but you're making extra work IMO. — FiveTools
– FiveTools, Commented Jul 19, 2011 at 11:50

Arsen Mkrtchyan · Accepted Answer · 2011-07-19 11:41:51Z

1

Use ClientScriptManager.RegisterStartupScript

See here for example

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
  public void Page_Load(Object sender, EventArgs e)
  {
    // Define the name and type of the client scripts on the page.
    String csname1 = "PopupScript";
    Type cstype = this.GetType();

    // Get a ClientScriptManager reference from the Page class.
    ClientScriptManager cs = Page.ClientScript;

    // Check to see if the startup script is already registered.
    if (!cs.IsStartupScriptRegistered(cstype, csname1))
    {
        StringBuilder cstext1 = new StringBuilder();
        cstext1.Append("<script type=text/javascript> alert('Hello World!') </");
        cstext1.Append("script>");

        cs.RegisterStartupScript(cstype, csname1, cstext1.ToString());
    }
  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>RegisterStartupScript</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    </div>
    </form>
</body>
</html>

Hope this helps

answered Jul 19, 2011 at 11:41

Arsen Mkrtchyan

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3 Comments

msfanboy Over a year ago

How is it possible to debug the javascript if its build dynamically?

Arsen Mkrtchyan Over a year ago

You can create not dynamically function, and call that function dynamically, it's just a sample @msfanboy

msfanboy Over a year ago

its not executed at the end of the page because the html control I search for is null.

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