INPUT ACCEPT NUMBERS ONLY
HTML
<input type="text" class="form-control" id="sales_gapy" name="sales_gapy" placeholder="Gap Y" onkeypress='return event.charCode >= 48 && event.charCode <= 57'>
<input type="text" class="form-control" id="sales_gapy" name="sales_gapy" placeholder="Gap Y" onkeypress='return event.charCode >= 48 && event.charCode <= 57'>