Adding css class through aspx code behind

I am using aspx. If I have HTML as follows:

<div id="classMe"></di开发者_运维技巧v>

I am hoping to dynamically add a css class through the code behind file, ie on Page_Load. Is it possible?

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If you want to add attributes, including the class, you need to set runat="server" on the tag.

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

Then in the code-behind:

classMe.Attributes.Add("class", "some-class")

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If you're not using the id for anything other than code-behind reference (since .net mangles the ids), you could use a panel control and reference it in your codebehind:

<asp:panel runat="server" id="classMe"></asp:panel>

classMe.cssClass = "someClass"

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Assuming your div has some CSS classes already...

<div id="classMe" CssClass="first"></div>

The following won't replace existing definitions:

ClassMe.CssClass += " second";

And if you are not sure until the very last moment...

string classes = ClassMe.CssClass;
ClassMe.CssClass += (classes == "") ? "second" : " second";

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BtnAdd.CssClass = "BtnCss";

BtnCss should be present in your Css File.

(reference of that Css File name should be added to the aspx if needed)

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controlName.CssClass="CSS Class Name";

working example follows below

txtBank.CssClass = "csError";

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Syntax:

controlName.CssClass="CSS Class Name";

Example:

txtBank.CssClass = "csError";

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If you want to retain the existing class, this would work:

string existingClass = classMe.Attributes["class"];
classMe.CssClass = existingClass + " some-class";