如果文本框 (First_Name) 留空，我会尝试出错。例如，如果名字字段留空，用户将收到以下错误:“请输入您的名字”，但在将该字段留空后单击提交按钮时没有任何反应...
<HTML>
<HEAD>
<TITLE>this is a test page</TITLE>
<script language="javascript" type="text/javascript">
<!--
function CheckForm()
{
var formObj = document.getElementById("Data");
var firstname = formObj.FIRST_Name.value;
if(notEmpty(firstname, "Please enter your first name")){
return true;}
return false;
}
function notEmpty(elem, helperMsg){
if(elem.value.length == 0){
alert(helperMsg);
elem.focus(); // set the focus to this input
return false;
}
return true;
}
</script>
</HEAD>
<BODY>
<div style="background: #CCCC99">
<HR><FORM id="Data" onsubmit="return CheckForm()" >
<P>First Name: <input type=text name=FIRST_Name maxlength=15 size=15>
</P>
<input type=submit value="Submit Products Registration Form" style="width: 220px"><input type=reset value="Reset">
</form>
</div>
</BODY>
</HTML>
最佳答案
firstname 是元素值，但您将它作为元素传递给 notEmpty，而不是使用
if(notEmpty(formObj.FIRST_Name, "Please enter your first name")){
关于javascript 错误消息未显示，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11660934/