How to write this Javascript coding in C# code behind?

Question

<%--Confirmation Box--%>
<script type="text/javascript" language="javascript">
    function alertbox() {

      if (confirm("Are you sure?") == true) 
          {
              document.getElementById('<%= hdnYesNo.ClientID %>').value = "YES";
          }
          else 
          {
              document.getElementById('<%= hdnYesNo.ClientID %>').value = "NO";
          }

        }
    </script>

How to rewrite this code in C# as codebehind? I would like have a confirm box with yes or no buttons.

Though there are scenarios that you need to build javascript server side,those scenarios are complex requirements and complex conditions. My answer and others here explained to you how to do what you wanted.I defended my answer under the basic pretense that you might be doing more advanced JS and your question merely uses something simple for the sake of clarity.After seeing the comment you just made below,and that you couldn't even fix the syntax of the selected answer code on your own,I know your a novice.Knowing that I can now say,why would you inject this Javascript server side? — Brian Ogden
– Brian Ogden, Commented Oct 11, 2013 at 6:38
It isn't right,you don't understand what you are doing.You should be keeping this <script> exactly where it is, on the aspx page or in a js file that you reference. ASP.NET is actually a beautiful framework, faster to code in than Ruby on Rails and more solid than PHP.But it is people like you who gives us a bad name because you don't understand the basics of web application coding and ASP.NET happens to have crazy nice tools that you can just slap stuff together if you hammer long enough. Try starting in PHP so that you cannot do something like you are currently trying to do. — Brian Ogden
– Brian Ogden, Commented Oct 11, 2013 at 6:43

Brian Ogden · Accepted Answer · 2013-10-10 09:35:50Z

11

protected void Page_Load(object sender, System.EventArgs e)
{    
    string csName = "PopupScript";
    Type csType = this.GetType();
    ClientScriptManager csm = Page.ClientScript;

    if (!csm.IsStartupScriptRegistered(csType, csName)) {
        StringBuilder sb = new StringBuilder();
        sb.Append("<script>");
        sb.Append("function alertbox() {");
        sb.Append("if (confirm('Are you sure?') == true) ");
        sb.Append("{");
            sb.Append("document.getElementById('" + hdnYesNo.ClientID + "').value = 'YES';");
        sb.Append("}");
        sb.Append("else");
        sb.Append("{");
        sb.Append("document.getElementById('" + hdnYesNo.ClientID + "').value = 'NO';");
        sb.Append("}");
        sb.Append("</script>");


        csm.RegisterStartupScript(csType, csName, sb.ToString());
    }
}

edited Oct 10, 2013 at 9:35

answered Oct 10, 2013 at 6:30

Brian Ogden

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3 Comments

zzzzBov Over a year ago

I'm downvoting this not because you didn't answer the question correctly, but because the practice of building JavaScript with server-side code is a terrible idea. Keep your JavaScript in .js files and make use of [data-*] attributes and <template> elements to pass data from the server to the script.

Brian Ogden Over a year ago

LOL And what if you are servicing users that can build their own custom websites and can add their own custom javascript with additional options in their admin panel. Yes you are mistaken and your opinion overlooks the myriad of reasons that someone might need to build their javascript server side. The real reason for your vote down is that you are not an ASP.NET developer and you just don't like the style.This feature of ASP.NET serves a useful purpose that just escapes you at the moment, it is maintainable and completely efficient based on particular needs of some projects. BOOM

Nguyễn Huy Over a year ago

I think this is correct answer for this question.Because this way can allow coder write javascript code with parameters.

kiran · Accepted Answer · 2013-10-11 06:31:21Z

2

you can use like this way

Page.ClientScript.RegisterStartupScript(this.GetType(), "Confi", "if(confirm('Are you sure?') == true){  document.getElementById('txtValue').value ='YES';}else{document.getElementById('txtValue').value ='NO';}", true);

edited Oct 11, 2013 at 6:31

answered Oct 10, 2013 at 6:33

kiran

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2 Comments

sifeee Over a year ago

thanks for your response i am gettin a error like ";" semicolon expected ERROR has occured can you rectify this

Brian Ogden Over a year ago

Geez man, I wrote out the exact working code for your javascript in C# and you chose his answer over mine and you can't even use his answer and fix the bug yourself.

Robert · Accepted Answer · 2013-10-10 06:36:53Z

1

You can use ClientScriptManager class and its methods, for example RegisterClientScriptBlock. Depends on when you want the javascript to execute.

See details here:

http://msdn.microsoft.com/en-us/library/System.Web.UI.ClientScriptManager_methods.aspx

edited Oct 10, 2013 at 6:36

answered Oct 10, 2013 at 6:30

Robert

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Comments

Maverick · Accepted Answer · 2013-10-10 21:37:09Z

1

You need javascript for this, it's not possible in code behind. Code behind is run on the server before the page is sent to the user, javascript is run on the user's computer.

If you want to get access to their answer in code behind (possible and straightforward), you can use ajax or you can postback.

If you want to have this popup to come up when you press on a .Net asp:button control, then you can put a javascript function in the "OnClientClick" attribute of the control.

EDIT: If you need help with any of the above, let us know and help will be provided :).

EDIT2: Due to the discussion below, I guess I should clarify: You can (obviously) construct javascript on the server side before passing it to the client, but the example you gave is NOT a case where you should be doing that (an example of where this might be a good idea would be a script that has variables read from a database or something similar that doesn't need to be dynamic between page loads).

edited Oct 10, 2013 at 21:37

answered Oct 10, 2013 at 6:30

Maverick

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7 Comments

Kristof Over a year ago

It kinda is, all of the other answers suggest to build the javascript server side so in the end the popup is still run client side with javascript and not with server side code.

Brian Ogden Over a year ago

You don't exactly understand. The RegisterStartUpScript in code behind usage creates the Javascript server side before the response is sent back to the client. If for example you need to do a database query and create your javascript dynamically based on the varying results of that database query, in code behind with RegisterStartUpScript is one way to do this, the javascript is "injected" into the response back to the client and whatever javascript was created and "injected" IS javascript that executes client side in the browser.

Kristof Over a year ago

I understand what they are doing but i still aggree with MrNoob. With the information specified in the question i would advise him not to build the script server side, it's more complex and there currently is no benefit as the end result will be the same but less clean. Saying his answer is not correct is wrong because he claims that you need javascript(which you do as you can see by the answers).

Brian Ogden Over a year ago

It doesn't answer the question lol. In fact MrNoob's answer states it is not possible in code behind which is false. Furthermore there are plenty of reasons someone needs to build their javascript in code behind, with a string builder and then "inject". And RegisterStartUpScript happens to be a clean way to do it, depending on how dynamic and complex the javascript might be.

Brian Ogden Over a year ago

Perhaps the user is only given a simplified javascript snippet to keep his question concise for the larger goal of building some more complex javascript that he/she doesn't want to nest in a aspx page if or switch statement as it might duplicate the core javascript in an if block and than again in an else block on the aspx page. That is why the question can be answered without conjecture about whether it is the cleanest way to go about it.

|

Giuseppe B · Accepted Answer · 2014-10-10 15:52:53Z

0

another option is to create the script in the /View folder and user razor for generating the script.

then you could point to the page in the tag like

<script src="~/ScriptGenerator/MyScript" />

for pointing the controller ScriptGeneratorController that expose the action MyScript

answered Oct 10, 2014 at 15:52

Giuseppe B

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