controlling javascript in asp.net, C#

**PRR** · May 22 '09, 10:41 AM

Write a JavaScript function...

**searockruz** · May 23 '09, 05:27 AM

Code:

if(condition)
{
ScriptManager.RegisterClientScriptBlock(this,this.GetType(),"HelloWorld","javascript:alert('Hello World');",true);
}

**jay123** · May 23 '09, 09:11 AM

Originally posted by searockruz

Code:

if(condition)
{
ScriptManager.RegisterClientScriptBlock(this,this.GetType(),"HelloWorld","javascript:alert('Hello World');",true);
}

thanks searockruz for ur reply, but where should i write this code.

in a button click event, in html javascript code or somewhere else

**searockruz** · May 23 '09, 04:03 PM

in the button click event inside your if condition

**Frinavale** · May 25 '09, 02:48 PM

Originally posted by jay123

thanks searockruz for ur reply, but where should i write this code.

in a button click event, in html javascript code or somewhere else

Hi Jay :)

You can place the function in several different places.
You could place it in an external .js file, you could place it in the <head> or <body> section of your page... It all depends on what you prefer and when you need to call the function.

In your case it doesn't really matter where you put it (because you're calling the function after the page has been loaded in the browser)...so just pick one

Your function should look something like the following (which checks some condition and if that condition is met will prompt the user to confirm their action):

JavaScript Code:

Code:

function ConfirmSave(){
  if(someCondition)
  {
    return confirm('Are you sure?');
  }

 return true;
}

Like I said this can go pretty much anywhere on your page...

You call the function in your onclientclick event:

Code:

<asp:Button ID="Savebutton" runat="server" OnClick="Savebutton_Click"  OnClientClick="return ConfirmSave();" />

-Frinny

**jay123** · May 26 '09, 08:18 AM

Originally posted by searockruz

Code:

if(condition)
{
ScriptManager.RegisterClientScriptBlock(this,this.GetType(),"HelloWorld","javascript:alert('Hello World');",true);
}

hi searockruz,
i did try ur code but it didnt help or rather it doesnt do anything

this is what i did:

if(condition)
{
ur script code
}

now whats happeneing is user gets a msg as "r u sure?" and now how does user close this message?? moreover this code runs after whole coding in that button click runs, so elimanating the whole meaning of msg given to user.

**jay123** · May 26 '09, 08:25 AM

Originally posted by Frinavale

Hi Jay :)

You can place the function in several different places.
You could place it in an external .js file, you could place it in the <head> or <body> section of your page... It all depends on what you prefer and when you need to call the function.

In your case it doesn't really matter where you put it (because you're calling the function after the page has been loaded in the browser)...so just pick one

Your function should look something like the following (which checks some condition and if that condition is met will prompt the user to confirm their action):

JavaScript Code:

Code:

function ConfirmSave(){
  if(someCondition)
  {
    return confirm('Are you sure?');
  }

 return true;
}

Like I said this can go pretty much anywhere on your page...

You call the function in your onclientclick event:

Code:

<asp:Button ID="Savebutton" runat="server" OnClick="Savebutton_Click"  OnClientClick="return ConfirmSave();" />

-Frinny

thanks frinny,

i have been trying ur option given earlier, but perhaps i am not that good in wrting javascript code. my requirement is

when a page loads initially i have stored a value of one of the dropdown control in a viewstate, and then after making some changes to the page. when user tries to save that page. that same drop down value is compared to viewstate value, if they are equal. user dont get any msg else a msg is shown to him that "r u sure?".

now that viewstate value has been stored in a Literal on page laod named Lit

i have tried this coding

Code:

if(document.getElementById("ctl00_ContentPlaceHolder1_dropdown1").value != document.getElementById("Lit").Value)
         {
             alert('r u sure?');
             return false;
         }

but to no use.
any help

**jay123** · May 26 '09, 10:22 AM

thanks everyone, hwo took some time to answer my question. the answer given by everyone was to some extend correct. its just my javascript basics need to be polished.

couple of things on which i wasted some time and wont like ant one of u to waste is:

1) label doesnt have value property in javascript, if we want to assign or retrieve value from label. we should use innertext property.

2) for dropdown use

Code:

var dd1 = document.getElementById("ctl00_ContentPlaceHolder1_dropdown1");
         var dd2 = dd1.selectedIndex;
         var dd3 = dd1.options[dd2].value;

where "ctl00_ContentP laceHolder1_dro pdown1" is a HTML name of dropdown taken from source of a page, and at end dd3 will have value of selectedindex of dropdown.

**Frinavale** · May 26 '09, 01:15 PM

:) I'm glad you sorted it out Jay.

The reason your DropDownList has an id of "ctl00_ContentP laceHolder1_dro pdown1" is because you're using a master page (or place holder). The ContentPlaceHol der control gives every control in it a unique name so that you can have a DropDownList named "dropdown1" in a content (aspx) page being displayed in ContentPlaceHol der1 and you have another DropDownList named "dropdown1" in another content (aspx) page being displayed in ContentPlaceHol der2.

The way to reference the "ctl00_ContentP laceHolder1_dro pdown1" in code is through the ClientID of the control.

For example, you would place the following in your asp code:

Code:

var dropDownClientID = "<%=dropdown1.ClientID %>";
var dd1 = document.getElementById(dropDownClientID);
var dd2 = dd1.selectedIndex;
var dd3 = dd1.options[dd2].value;

Please note that <%= is short hand for Response.Write( )....so the above code writes the ClientID of dropdown1 into the page (into your JavaScript) at compile/runtime.

It's true that an ASP label doesn't have a value property in JavaScript. The reason is because ASP Labels are rendered as <span> tags. If you want access to the text/content being displayed in a <span> tag you have to use the innerHTML property (or innerText property as you have discovered).

For example:

Code:

var labelClientID = "<%=Label1.ClientID %>";
var labelSpan = document.getElementById(labelClientID);
var labelText = labelSpan.innerHTML;
alert(labelText);

One more thing to note is that I don't think that you can access things stored in ViewState in your JavaScript (since it's encrypted). Instead use HiddenFields.

**jay123** · May 26 '09, 03:26 PM

thanks frinny,
hats off to your clear ideas and simple writing technique u have. yah i forgot to mention but i did use hidden fields to compare values.

Cheers and thanks a lot for replying.

controlling javascript in asp.net, C#

controlling javascript in asp.net, C#

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