This is the function to validate for the number when a key is pressed to fill the input field.
HTML
<div class="wrapper">
<form method="" name="" >
<input type="text" value="" name="" class="inp_valid">
<span id="num_validate">Please enter a valid number.</span>
</form>
</div>
Javascript
jQuery.fn.NumericOnly = function() {
return this.each(function()
{
$(this).keydown(function(e)
{
var key = e.charCode || e.keyCode || 0;
// allow backspace, tab, delete, enter, arrows, numbers and keypad numbers ONLY
// home, end, period, and numpad decimal
if ( key == 8 || key == 9 || key == 13 || key == 46 || key == 110 || key == 190 || (key >= 35 && key <= 40) || (key >= 48 && key <= 57) || (key >= 96 && key <= 105)) {
jQuery('#num_validate').hide();
return true;
}else {
jQuery('#num_validate').show();
return false;
}
});
});
};
jQuery(".inp_valid").NumericOnly();