How to allow only integers in a textbox? [duplicate]

Answer 1

if (document.de.your_textbox_id.value != "")

{          
   var checkOK = "0123456789";
   var checkStr = document.de.your_textbox_id.value;        
   var allValid = true;
   for (i = 0;  i < checkStr.length;  i++)
   {
    ch = checkStr.charAt(i);           
    for (j = 0;  j < checkOK.length;  j++)
    if (ch == checkOK.charAt(j))
    break;
    if (j == checkOK.length)
      {
       allValid = false;
       break;
      }
    }      
    if (!allValid)
    {           
       alert("Please enter only numeric characters in the text box.");
       document.de.your_textbox_id.focus();                            
    }
}

Answer 2

I would use ASP.NET Ajax Filter TextBoxExtender control

https://www.aspsnippets.com/Articles/ASPNet-AJAX-FilteredTextBoxExtender-Control-Example.aspx

Answer 3

An even easier method is to use the TextMode attribute:

<asp:TextBox runat="server" ID="txtTextBox" TextMode="Number">

Answer 4

User below regular expression validator.

    <asp:RegularExpressionValidator ID="RegularExpressionValidatorNumeric" runat="server" ControlToValidate="yourControl ID" ErrorMessage="Registraion ID Should be a Numeric" ValidationExpression="^\d+$"  ></asp:RegularExpressionValidator>

Answer 5

It can be done with a compare validator as below. Unlike the other answers, this also allows negative numbers to be entered, which is valid for integer values.

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:CompareValidator ControlToValidate="TextBox1" runat="server" ErrorMessage="Integers only please" Operator="DataTypeCheck" Type="Integer" ></asp:CompareValidator>

Answer 6

Just use

<input type="number" id="foo" runat="server" />

It'll work on all modern browsers except IE +10. Here is a full list:

http://caniuse.com/#feat=input-number