how to determine which textbox is focused and add text to it?

Question

I am creating web application in asp.net. I have 5 text box which are asp controls. I want to get which text box having focus on that time and then when I am press "add" button, the "hello" text has to added to the particular text box which are got focused before pressed the "add" button.

I need Asp.net (with C# code) to move to my next step

Is this what you mean? http://stackoverflow.com/questions/497094/how-do-i-find-out-which-dom-element-has-the-focus — Mark Hughes, Mar 25 '15 at 06:27

user2316116 · Answer 1 · 2015-03-25T11:33:36.230

0

Since the last focus will be on the Add button, you need to "remember" the TextBox before the Button is clicked.

Try to use onfocus() event.

<!-- Add a HiddenField control to "remember" the id of a TextBox -->
<asp:HiddenField ID="HiddenField1" runat="server" />  

<!-- Assign current focus to that hidden field -->
<asp:TextBox onfocus="document.getElementById('HiddenField1').value=this.id" ...>
<asp:TextBox onfocus="document.getElementById('HiddenField1').value=this.id" ...>

If that works, you will be able to get a value in code-behind as

string c = HiddenField1.Value;

if (!string.IsNullOrEmpty(c)) 
   if (c == "TextBox1")
      TextBox1.Text = "hi there";

Note: depends on your environment you might need to call ClientID (e.g. getElementById('<%=HiddenField1.ClientID%>')

UPDATE

As I told you above you might need to use HiddenField1.ClientID to find the HiddenField Control. When your source looks as

<input type="hidden" name="ctl00$MainContent$HiddenField1" id="MainContent_HiddenField1" /> 

<input name="ctl00$MainContent$TextBox1" type="text" id="MainContent_TextBox1" 
    onfocus="document.getElementById(&#39;HiddenField1&#39;).value=this.id" />    
<input name="ctl00$MainContent$TextBox2" type="text" id="MainContent_TextBox2" 
    onfocus="document.getElementById(&#39;HiddenField1&#39;).value=this.id" /> 

<input type="submit" name="ctl00$MainContent$Button1" value="Button" id="MainContent_Button1" />

That means that you use MasterPage and asp.net changes id of your control to MainContent_HiddenField1. So when you use document.getElementById('HiddenField1') it will not find such control because its id is different. You either need to use

document.getElementById('MainContent_Button1').value=this.id

which will work but might require changes if you remove master page or will move the textbox to other container

or use

document.getElementById('<%=HiddenField1.ClientID%>').value=this.id

which will automatically inject correct id (recommended asp.net way)

edited Mar 25 '15 at 11:33

answered Mar 25 '15 at 07:57

user2316116

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Thank you. while I am try to use your code, It shows error like "Microsoft JScript runtime error: 'document.getElementById(...)' is null or not an object". What to do ? – Santhosh Legent Mar 25 '15 at 08:41
Did you try to change `getElementById('<%=HiddenField1.ClientID%>')` as suggested above? The error means that 'HiddenField1' cannot be found which means that asp.net dynamically changed it to some other id. – user2316116 Mar 25 '15 at 08:50
I tried "getElementById('<%=HiddenField1.ClientID%>')" also, same error getting – Santhosh Legent Mar 25 '15 at 08:58
Open aspx page in the browser, right click, View Source. Copy and paste the html code related to HiddenField as well as TextBox controls here. – user2316116 Mar 25 '15 at 09:02
Its is not working in IE. But chrome it supporting. Thank you. – Santhosh Legent Mar 25 '15 at 09:02
I was select on text box and click add Button. The string c = HiddenField1.Value; while tried to debug this line , the "c" value show as "NULL" value. – Santhosh Legent Mar 25 '15 at 09:04
It should work, see http://stackoverflow.com/questions/27421475/get-updated-hiddenfield-value-in-code-behind It might be due to your page setup. I'd suggest to create a new simple aspx with only required controls and test. – user2316116 Mar 25 '15 at 09:09
I found the problem why hidden value is not properly updated. when i am using – Santhosh Legent Mar 25 '15 at 09:52
I am using VS2010. What to do ? – Santhosh Legent Mar 25 '15 at 09:52
"The onfoucse funtion is not the property of Textbox." -- what do you mean by this? – user2316116 Mar 25 '15 at 10:02
I am getting validation error " onfocus is not a textbox property" – Santhosh Legent Mar 25 '15 at 10:06
It's just a warning message in VS.NET, and not the error, isn't it? If you want to avoid that warning you could set onfocus from the code-behind using `TextBox1.Attributes.Add("onfocus", "document.getElementById('HiddenField1').value=this.id");` – user2316116 Mar 25 '15 at 10:09
I was added that code in page load. Still the variable C" value is Null only – Santhosh Legent Mar 25 '15 at 10:27
Open aspx page in the browser, right click, View Source. Copy and paste the html code 1) related to HiddenField 2) as well as your TextBox controls here. – user2316116 Mar 25 '15 at 10:53
` ` – Santhosh Legent Mar 25 '15 at 11:15
As I told you from the very beginning you should use ClientID property. See updated answer. – user2316116 Mar 25 '15 at 11:34

how to determine which textbox is focused and add text to it?

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