Question

我会尽力解释这个问题。好的，所以这是我的代码：

function validation() {

    var name = document.getElementById("name").value;
    var email = document.getElementById("email").value;
    var subject = document.getElementById("subject").value;
    var message = document.getElementById("message").value;
    var at = "@";
    var dot = ".";
    var lat = email.indexOf(at);
    var lstr = email.length;
    var ldot = email.indexOf(dot);

    var success = true;

    if (name == null || name == "") {
        success = false;
        document.getElementById("name-error").innerHTML = "I want to know who you are!";
    }

    if (document.contact.name.value.length <= 5) {
        success = false;
        document.getElementById("name-error").innerHTML = "Full name, please!";
    }

    if (email.indexOf(at) == -1 || email.indexOf(at) == 0 || email.indexOf(at) == lstr) {
        success = false;
        document.getElementById("email-error").innerHTML = "That's not an email!";
    }

    if (email == null || email == "") {
        success = false;
        document.getElementById("email-error").innerHTML = "Give me your email!";
    }

    if (document.contact.email.value.length <= 8) {
        success = false;
        document.getElementById("email-error").innerHTML = "Email is too short!";
    }

    if (subject == null || subject == "") {
        success = false;
        document.getElementById("subject-error").innerHTML = "I need a subject!";
    }

    if (document.contact.subject.value.length <= 5) {
        success = false;
        document.getElementById("subject-error").innerHTML = "A longer subject would be nice.";
    }

    if (message == null || message == "") {
        success = false;
        document.getElementById("message-error").innerHTML = "Don't forget your message!";
    }

    if (document.contact.message.value.length <= 30) {
        success = false;
        document.getElementById("message-error").innerHTML = "Your message is too concise!";
    }

    return success;

}

我的问题是，即使id的值为空，它仍然表示它太短。例如，当我单击发送按钮时，它表示名称字段太短，即使它是空的。我以为我说如果名字==“”（这是空的），说“我想知道你是谁！”。但是现在，它只是说，“全名请”，如果名称的值是＆lt; = 5，则显示为suppost ...而不是当它为空时。得到我在说什么？

Answer 1

将其变为elseif而不是具有两个独立的独立条件：

if(name == null || name == "") {
success = false;
  document.getElementById("name-error").innerHTML = "I want to know who you are!";
}
else if(document.contact.name.value.length <= 5) {
 success = false;
document.getElementById("name-error").innerHTML = "Full name, please!";  
}

Answer 2

您提到与字段相关的所有条件仅为if，但实际上您需要将其视为if.. else或if... else if.. else语句。

如果你只提及if语句，那么它将执行一个字段的所有相关代码，并且它将显示你分配给innerHTML的后一个值，它总是“电子邮件太短！“在您的”电子邮件字段“条件中。

Answer 3

这是您的修正代码：

<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Form validation</title>
<script>
function validation() {

    var name = document.getElementById("name").value.trim();
    var email = document.getElementById("email").value.trim();
    var subject = document.getElementById("subject").value.trim();
    var message = document.getElementById("message").value.trim();
    var at = "@";
    var dot = ".";
    var lat = email.indexOf(at);
    var lstr = email.length;
    var ldot = email.indexOf(dot);

    var success = true;

    if(name == null || (name.length)==0) {
        success = false;
        document.getElementById("name-error").innerHTML = "I want to know who you are!";
    }else{          
        document.getElementById("name-error").innerHTML = "";
    }

    if(name.length > 1 && document.contact.name.value.length < 5) {
        success = false;
        document.getElementById("name-error").innerHTML = "Full name, please!";  
    }

    if(email == null || email.length==0) {
        success = false;
        document.getElementById("email-error").innerHTML = "Give me your email!";
    }else{
        document.getElementById("email-error").innerHTML = "";
    }       

    if(email.length > 1 && document.contact.email.value.length <= 8){
        success = false;
        document.getElementById("email-error").innerHTML = "Email is too short!";     
    }

    if(email.length > 8 && email.indexOf(at) == -1 || email.indexOf(at) == 0 || email.indexOf(at) == lstr){
        success = false;
        document.getElementById("email-error").innerHTML = "That's not an email!";
    }   

    if(subject == null || subject.length==0) {
        success = false;
        document.getElementById("subject-error").innerHTML = "I need a subject!";
    }else{
        document.getElementById("subject-error").innerHTML = "";
    }

    if(subject.length > 0 && document.contact.subject.value.length <= 5){
        success = false;
        document.getElementById("subject-error").innerHTML = "A longer subject would be nice.";  
    }

    if(message == null || message.length==0) {
        success = false;
        document.getElementById("message-error").innerHTML = "Don't forget your message!";
    }else{
        document.getElementById("message-error").innerHTML = "";
    }

    if(message.length > 0 && document.contact.message.value.length <= 30){
        success = false;
        document.getElementById("message-error").innerHTML = "Your message is too concise!"; 
    }

    return success;

}
</script>
</head>
<body>
<form action="" method="post" name='contact'>
    <input type="text" name="name" id="name" value=''/>
    <span id="name-error"></span>
    <br />
    <input type="text" name="email" id="email" value=''/>
    <span id="email-error"></span>
    <br />
    <input type="text" name="subject" id="subject" value=''/>
    <span id="subject-error"></span>
    <br />
    <input type="text" name="message" id="message" value=''/>
    <span id="message-error"></span>
    <br />
    <input type="button" value="Send" onclick='return validation();'>
</form>

</body>
</html>

Fiddle DEMO

当字段值为空时，它表示它太短了！（JavaScript）的

3 个答案:

当字段值为空时，它表示它太短了！ （JavaScript）的

3 个答案:

当字段值为空时，它表示它太短了！（JavaScript）的