当字段值为空时，表示它太短！（Javascript）

我会试着尽我所能解释这一点。好了，这里是我的代码：当字段值为空时，表示它太短！（Javascript）

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，即使在id的值是空的，它仍然说，这是太短了。例如，当我点击发送按钮时，它说域名太短，即使它是空的。我以为我说过，如果name ==“”（它是空的），请说“我想知道你是谁！”。但是现在，它只是说，如果名称的值是< = 5 ...，当它是空的时，应该显示suppost以显示“请填写全名”。知道我在说什么？

来源

2013-06-12 Matthew

使用'其他if's。这样，只有一个错误将会是'innerHTML'。而不是在每个块中设置成功false，最初保持为false。 –

您提到与字段相关的所有条件仅为if，但实际上您需要将它们提及为if.. else或if... else if.. else语句。

如果你只提if语句，然后它会执行所有相关的代码字段和atlast它会显示你指定给innerHTML这始终是后者的值“电子邮件是太短了！”在你的“电子邮件字段”状态。

来源

2013-06-12 06:21:19

啊，我明白了。所以我应该说，如果name ==“”这样做，否则如果name <= 5那么做？ – Matthew

@MattKnowsTech是 –

使之成为一个elseif而不是有两个分开独立的条件：

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!"; 
}

来源

2013-06-12 06:21:36 MrCode

'别的if'，不'elseif' –

临屋的标签上写着'的JavaScript！= php' – stUrb

你引用的PHP文档，而我们正在谈论的JavaScript？ – g00glen00b

这是您的修复代码：

<!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

来源

2013-06-12 07:50:49

当字段值为空时，表示它太短！ （Javascript）

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当字段值为空时，表示它太短！（Javascript）