Form表單資料檢查，防止直接送出

Example1：
<form name="theForm" id="theForm" method="post" action="do.php">
  <label for="name">Name:</label>
  <input type="text" name="name" id="name" />
  <input type="button" name="send" id="send" value="送出" onClick="checkForm();" />
</form>

function checkForm()
{
    var frm = document.forms["theForm"];
    if(frm.name.value == "")
    {
        alert("Error:name is null");
    }else{
        frm.submit();
    }
}

Example2：
<form name="theForm" id="theForm" method="post" action="do.php" onSubmit="return checkForm(this);">
  <label for="name">Name:</label>
  <input type="text" name="name" id="name" />
  <input type="submit" name="send" id="send" value="送出" />
</form>

function checkForm()
{
    var frm = document.forms["theForm"];
    if(frm.name.value == "")
    {
        alert("Error:name is null");
        return false;
    }else{
        return true;
    }
}