我有一个简单的表格，其中包含名字和姓氏以及称呼的字段。我有一个 javascript 函数，它应该验证字段是否为空或超过 25 个字符。该功能主要适用于 .focus(); 页面只是重新加载。不知道我做错了什么，请指教。提前致谢。
function validate(){
//alert ("TEST!!!");
var first = document.getElementById('firstname').value;
if (first.length == 0 || first.length > 25){
alert ("Please enter your first name, no longer than 25 chracters.");
document.getElementById('firstname').focus();
return false;
}
var last = document.getElementById('lastname').value;
if (last.length == 0 || last.length > 25){
alert ("Please enter your last name, no longer than 25 characters.");
document.getElementsByName('lastname').focus();
return false;
}
var title = document.getElementById('title').value;
if (document.getElementById('title').selectedIndex == 0){
alert ("Please select your salutation");
document.getElementById('title').focus();
return false;
}
return true;
}
在 html 中，表单是：
<form name="name" form id="name" method="post" onsubmit="validate();">
Salutation: <select name="title" select id="title">
<option selected="Please Select">Please select</option>
<option value="Mr.">Mr.</option>
<option value="Mrs.">Mrs.</option>
<option value="Miss">Miss</option>
</select><br><br>
First Name : <input type="text" input id="firstname" name="firstname">
Last Name : <input type="text" input id="lastname" name="lastname"><br><br>
<input type="submit" value="Submit"><br><br>
</form>