JavaScript to accept only numbers between 0 to 255 range

Question

My Requirement is to validate the ip ranges, I need to create a JavaScript function to accept only numeric and it must allow only between the range 0 to 255. If anything is ente

Answer 1

I would rather go instantly for validation of whole ip address. Allowing input both numbers and dots, parsing them thru REGEX pattern.

Pattern usage example you could fetch here: http://www.darian-brown.com/validate-ip-addresses-javascript-and-php-example/

The code itself would look something like:

<input type='text' id='numonly' value="" onkeypress='allowIp(event)' onkeyup='javascript:checkIp()'>

function allowIp(e){
if((e.keyCode < 48 || e.keyCode > 57) && e.keyCode != 46)  // both nubmer range and period allowed, otherwise prevent.
  { 
      e.preventDefault();
  }
}

function checkIp() 
{ 
  var ip = $("#numonly").val();

    /* The regular expression pattern */
  var pattern = new RegExp("^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.)(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.)(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.)([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$");

  /* use  javascript's test() function to execute the regular expression and then store the result - which is either true or false */
  var bValidIP = pattern.test(ip);

  if(bValidIP){
     // IP has ok pattern
     $("#numonly").css("background", "green");
  }
  else {
     $("#numonly").css("background", "red");
  }
}

You could check it here on fiddle http://jsfiddle.net/Indias/P3Uwg/

Answer 2

    function fun_key()
    {
    var key=event.keyCode;
    if(key>=48 && key<=57)
    {
    return true;
    }
    else
    {
    return false;
    alert("please enter only number");
    }
    }

    and you can call this function on keypress event like:
    <asp:textbox id="txtphonenumber" runat="server" onkeypress="return fun_key()">                </asp"textbox>