Javascript Code:
function specialcharecter()
{
var iChars = "!`@#$%^&*()+=-[]\\\';,./{}|\":<>?~_";
var data = document.getElementById("txtCallSign").value;
for (var i = 0; i < data.length; i++)
{
if (iChars.indexOf(data.charAt(i)) != -1)
{
alert ("Your string has special characters. \nThese are not allowed.");
document.getElementById("txtCallSign").value = "";
return false;
}
}
}
Note: ‘txtCallSign’ is the Id of the textbox.