Thom Robbins' .NET Weblog

Friday, January 02, 2004

Received the following question that I thought would post:

I am doing an ASP.NET Web Page and can’t seem to figure out how to put a line

break in. I used to used VBCR, but for some reason it just doesn’t seem to work?

What is up?

Actually the answer is – HTML. Within ASP.NET label controls understand imbedded

HTML within controls. So for example, if I wanted to place a break and maybe do

some formatting within a label control I could use the following code.

Label1.Text = "<h1>This is the first line </h1><br>"

Label1.Text &= "<h2>This is the second line</h2> <br>"

9:52:14 PM

ASP.NET includes an extremely rich object model that covers most of what developers

need for their development. The downside of the server side centric object model is

that once a page is rendered to HTML on the client, there is no way to run any

additional code until a server side postback is completed. Often this extra tip is not

something that is desirable.

Even though .NET doesn’t directly include any object references for directly creating

JavaScript. You do have the ability to insert JavaScript code into a string and then

inserted into the HTML and can be triggered from the client side. Some of the most

common client side events are shown below.

OnFocus – Occurs when a control receives focus

OnBlur – Occurs when focus leaves a control

OnClick – Occurs when the user clicks on a control

OnChange – Occurs when the user changes value of certain controls

OnMouseOver – Occurs when the user moves the mouse pointer over a control

The code needed to insert script is added to the page load event of the web form.

For example, here is an example of adding a JavaScript alert to a page using the

OnMouseOver event.

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles MyBase.Load

'Create the variable that included the script

Dim ClientScript As String = "<script language=JavaScript>

function ShowInfo() {alert('Pointer on the control'); }</script>"

' register the script on the page

If (Not IsClientScriptBlockRegistered("ShowInfo")) Then

RegisterClientScriptBlock("ShowInfo", ClientScript)

End If

TextBox1.Attributes.Add("onMouseOver", "ShowInfo()")

End Sub

When the page is rendered the HTML now contains the script block as shown below.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<HTML>

<HEAD>

<title>TestForm</title>

Studio .NET 7.1">

7.1">

content="JavaScript">

content="http://schemas.microsoft.com/intellisense/ie5">

</HEAD>

<form name="Form1" method="post" action="TestForm.aspx"

id="Form1">

('Pointer on the control'); }</script>

<input name="TextBox1" type="text" id="TextBox1"

onMouseOver="ShowInfo()" style="Z-INDEX: 101; LEFT: 304px;

POSITION: absolute; TOP: 168px" />

</form>

</body>

</HTML>

9:32:16 PM