How to allow only numbers into textbox using javascript, asp.net , Allow only numbers validation using javascript

function numbersonly(e) {
var unicode = e.charCode ? e.charCode : e.keyCode
if (unicode != 8) { //if the key isn't the backspace key (which we should allow)
if (unicode < 48 || unicode > 57) //if not a number
return false //disable key press
}
}



asp:TextBox ID="tbxBkgRefNo" runat="server" onkeypress="return numbersonly(event);"