How to check if a asp text box is empty or not

Question

Possible Duplicate:
textbox empty check using javascript

I have a asp.net button and a asp.net textbox, when I click on button, I want to check if textbox is empty or not but not sure how I can do that,

<div>
    <asp:TextBox ID="txtEU" runat="server"></asp:TextBox>
</div>
<div>
    <asp:ImageButton ID="button" runat="server" OnClientClick="MyFunction(); return false;" ImageUrl="/myfolder/abc.png" />
</div>

in my JavaScript I am doing,

   <script type="text/javascript">
    function doWork() 
    {  
        if($input[]

not sure how to check if its empty or not, if its empty then I am doing something if not then it should call a code behind method for that button.

@huMptyduMpty is that question telling how to call a code behind method as well ? — Mathematics, Nov 23 '12 at 11:29
@huMptyduMpty This link you now posted asking me to have another button that will do a post back which I don't want in my case, I would suggest you to live in positive world with a positive mind you might get somewhere by chance :) — Mathematics, Nov 23 '12 at 11:34

score 13 · Accepted Answer · edited Feb 11 '15 at 14:59

13

Read on the ClientIDMode property to see how element ID are generated in ASP.NET (4.0 and above)

function doWork() 
{  
     var textbox = document.getElementById('<%=txtEU.ClientID%>');

     if(textbox.value.length == 0)
     {

     }
}

OR

if(textbox.value == "")

Using Validators will help you handle some of this validation out of the box. One of them is RequiredValidator, which evaluates the value of an input control to ensure that the user enters a value.

<asp:RequiredFieldValidator runat="server" ID="txtEURequiredValidator" ErrorMessage="EU should not be empty" />

edited Feb 11 '15 at 14:59

ѺȐeallү

2,887
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answered Nov 23 '12 at 11:29

codingbiz

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I think the best practice with asp.net is to use the validators. – Lionel D Nov 23 '12 at 11:39
I was focusing on the JavaScript challenge accessing controls in asp.net. Updated my answer. Thanks. – codingbiz Nov 23 '12 at 11:43

score 5 · Answer 2 · answered Nov 23 '12 at 11:29

you have the ability to use a RequiredFieldValidator or a CustomValidator if you need to execute a more complex scenario.

Here is a good starting point i think: http://asp.net-tutorials.com/validation/introduction/ (check the links on the right side to have a detailed view of the validators)

Hope this helps.

score 1 · Answer 3 · edited May 23 '17 at 12:09

1

You can do like so:

if ($('#<%= txtEU.ClientID %>').val()({
   // String is not empty
}

Explanation:

Because, by default, asp.net mangles the html ID for the text box, you will need to inject the name into your jQuery.
In jQuery, null and empty can both be tested for with !

edited May 23 '17 at 12:09

Community

1
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answered Nov 23 '12 at 11:31

StuartLC

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score 1 · Answer 4 · answered Nov 23 '12 at 11:37

 //javascript code
function Myfunction()
    {   
       if(document .getElementById("<%=txtEU.ClientID %>").value=="")
        {
            alert("Please Enter Text");
           txtEU.focus();
            return false;
        }

        return true;
    }
      //aspcode
 <asp:ImageButton ID="button" runat="server" OnClientClick="return Myfunction();" ImageUrl="/myfolder/abc.png" />

score 0 · Answer 5 · edited Nov 23 '12 at 13:25

0

if ($('#<%= yourtextboxname.ClientID %>').val() =="")
  // String is not empty
}

edited Nov 23 '12 at 13:25

bluish

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answered Nov 23 '12 at 13:07

Sharmaji TM

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How to check if a asp text box is empty or not

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