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();                            
    }
}