问如何使用javascript验证文本字段

EN

<form namme="frms" action="booking_management.php">
    <input type="text" name="total" id="totald" value="" onkeyup="calbill()" class="input"/>
    <input name="but" type="button" value="Send Bill" class="btn btn-primary" onClick="bill()" />
</form>

function bill() {
  if (Checktot()) {
    document.forms["frms"].submit();
  }
}

function Checktot() {
  var tot = document.getElementById("totald").value;
  if (tot == "no") {
    document.getElementById("totald").style.borderColor = "#ED291F";
    alert("Please try again");
    return false;
  }
  return true;

}