asp.net textbox with java script problem

Question

I'm trying to check if asp.net textbox is empty or not using java script. my code working ok but if I enter only numbers will conder it empty so I have either enter letters and numbers or only letters.

Please advice.

here is my code

 <script type="text/javascript">
function check(){
  var txt = document.getElementById('<%=txt.ClientID%>').value;

              //(isNaN(cmbStateHome) == false

              if (isNaN(txt) == false) {
                  alert("Please enter some thing.");

              }
              else {alert("ok");}
          }
}
</script> 


 <asp:TextBox ID="txt" runat="server"></asp:TextBox>
                <asp:TextBox ID="txtZipCodeHome" runat="server" Style="top: 361px; left: 88px; position: absolute;

<asp:LinkButton ID="LinkButton1" runat="server" OnClientClick="check()">LinkButton</asp:LinkButton>

Phil Rykoff · Accepted Answer · 2010-03-08 21:00:37Z

3

replace

          if (isNaN(txt) == false) {

by

          if (txt == "") {

for isNan look here:

The isNaN function evaluates an argument to determine if it is "NaN" (not a number).

answered Mar 8, 2010 at 21:00

Phil Rykoff

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Comments

AaronS · Accepted Answer · 2010-03-08 21:01:34Z

0

isNAN is checking to see if the input is a number. ie: Not a Number.

Because of this, it will return false if you enter only numbers.

You should replace that check to see if the text is equal to an empty string.

answered Mar 8, 2010 at 21:01

AaronS

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Kerido · Accepted Answer · 2010-03-08 21:04:39Z

0

Why don't you use if (txt.length == 0)?

answered Mar 8, 2010 at 21:04

Kerido

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Wallace Breza · Accepted Answer · 2010-03-08 22:16:24Z

0

Take a look at using the <asp:RequiredFieldValidator /> server control. It will automatically apply a regex to the field and stop the user from submitting the form if they have not filled in the text box.

Ex)

<asp:TextBox id="TextBox1" runat="server"/>
<asp:RequiredFieldValidator id="req1" ControlToValidate="TextBox1" runat="server" />
<asp:LinkButton id="Button1" Text="Do Something" runat="server" />

answered Mar 8, 2010 at 22:16

Wallace Breza

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