How to Edit CSS Style of a Div Using C# in .Net

How to edit CSS style of a div using C# in .NET

Add the runat="server" attribute to it so you have:

<div id="formSpinner" runat="server">
    <img src="images/spinner.gif">
    <p>Saving...</p>
</div>

That way you can access the class attribute by using:

formSpinner.Attributes["class"] = "classOfYourChoice";

It's also worth mentioning that the asp:Panel control is virtually synonymous (at least as far as rendered markup is concerned) with div, so you could also do:

<asp:Panel id="formSpinner" runat="server">
    <img src="images/spinner.gif">
    <p>Saving...</p>
</asp:Panel>

Which then enables you to write:

formSpinner.CssClass = "classOfYourChoice";

This gives you more defined access to the property and there are others that may, or may not, be of use to you.

How do you modify a CSS style in the code behind file for divs in ASP.NET?

testSpace.Style.Add("display", "none");

Set the css class of a div using code behind

C#

divControl.Attributes["class"] = "myClass";

VB

divControl.Attributes("class") = "myClass"

You'll need to have a rule like this one on your css file

.myClass
{
   height:200px; 
   /*...more styles*/
}

Change CSS in backend

myDiv.Attributes.CssStyle.Add("color", "white");

This is how I do by adding CSS for the same based on the condition.

Div style changing using asp.net C# code

First give an id to your div like this

<div runat="server" id="div1"></div> 

And then in your C# code write this to add style to div.

string style = div1.Style[HtmlTextWriterStyle.Display];

if(style.ToLower()=="none")
   div1.Style.Add(HtmlTextWriterStyle.Display, "block");

And here is how you can remove style.

div1.Style.Remove(HtmlTextWriterStyle.Display);

Changing CSS style from ASP.NET code

C#, because I don't want to typo the VB syntax.

Markup:

<div runat="server" id="divControl">...</div>

Class of the Page:

protected System.Web.UI.HtmlControls.HtmlGenericControl divControl;

OnLoad/Other function:

divControl.Style.Add("height", number / anotherNumer);

How do you change the style of a div programmatically

If you want to alter the color of the div with client side code (javascript) running in the browser, you do something like the following:

<script>
 var fooElement = document.getElementById("foo");
 fooElement.style.color = "red"; //to change the font color
</script>

Add CSS class to a div in code behind

What if:

 <asp:Button ID="Button1" runat="server" CssClass="test1 test3 test-test" />

To add or remove a class, instead of overwriting all classes with

   BtnventCss.CssClass = "hom_but_a"

keep the HTML correct:

    string classname = "TestClass";

    // Add a class
    BtnventCss.CssClass = String.Join(" ", Button1
               .CssClass
               .Split(' ')
               .Except(new string[]{"",classname})
               .Concat(new string[]{classname})
               .ToArray()
       );

     // Remove a class
     BtnventCss.CssClass = String.Join(" ", Button1
               .CssClass
               .Split(' ')
               .Except(new string[]{"",classname})
               .ToArray()
       );

This assures

• The original classnames remain.
• There are no double classnames
• There are no disturbing extra spaces

Especially when client-side development is using several classnames on one element.

In your example, use

   string classname = "TestClass";

    // Add a class
    Button1.Attributes.Add("class", String.Join(" ", Button1
               .Attributes["class"]
               .Split(' ')
               .Except(new string[]{"",classname})
               .Concat(new string[]{classname})
               .ToArray()
       ));

     // Remove a class
     Button1.Attributes.Add("class", String.Join(" ", Button1
               .Attributes["class"]
               .Split(' ')
               .Except(new string[]{"",classname})
               .ToArray()
       ));

You should wrap this in a method/property ;)

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