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我正在制作一个将发送电子邮件的联系表格，但我无法确保人们确实在输入数据（我知道我需要进行更深入的验证，但我想确保它首先工作）。当用户单击发送时，javascript 将检查以确保字段已填写。如果是这样，那么它将在服务器端再次验证，然后发送消息（这工作正常），如果不是，它将显示警报并且它不应该发送消息。
但是，使用此 javascript，如果字段为空，它将显示错误消息，然后仍然发送电子邮件。我在这里做错了什么？

<script type="text/javascript">
                function validate() {
                    var x=document.forms['mailcontact']['name'].value; 
                    var y=document.forms['mailcontact']['email'].value; 
                    var z=document.forms['mailcontact']['subject'].value; 
                    if (x == '' || x == null || x == ' name') {
                        alert("You need to enter a name");
                    }
                    else if (y == '' || y == null || y == ' email') {
                        alert("You need to enter your email");
                    }
                    else if (z == '' || z == null || z == ' subject') {
                        alert("You need to enter a subject line");
                    }   
                    else {
                        document.forms['maincontact'].submit();
                    }
                }
            </script>

            <form method="POST" action="mail.php" id="mailcontact">
                <input value=" name" size="25" id="contactname" type="text" name="name" onblur="if(this.value=='') this.value=' name';" onfocus="if(this.value==' name') this.value='';" /> 
                <input value=" email" size="25" id="contactemail" type="text" name="email" onblur="if(this.value=='') this.value=' email';" onfocus="if(this.value==' email') this.value='';" />
                <input value=" subject" size="25" id="contactsubject" type="text" name="subject" onblur="if(this.value=='') this.value=' subject';" onfocus="if(this.value==' subject') this.value='';" />
                <textarea name="message"> message</textarea>
                <input onclick="validate()" value="validate_then_send" type="image" src="../images/sendbutton.png" style=" width: 200px; border: none; position: relative; left: 360px;" />
            </form>​
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1 回答 1

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<script type="text/javascript">
                function validate() {
                    var x=document.forms['mailcontact']['name'].value; 
                    var y=document.forms['mailcontact']['email'].value; 
                    var z=document.forms['mailcontact']['subject'].value; 
                    if (x == '' || x == null || x == ' name') {
                        alert("You need to enter a name");
                    }
                    else if (y == '' || y == null || y == ' email') {
                        alert("You need to enter your email");
                    }
                    else if (z == '' || z == null || z == ' subject') {
                        alert("You need to enter a subject line");
                    }   
                    else {
                        document.forms['maincontact'].submit();
                    }
                }
            </script>

            <form method="POST" action="mail.php" id="mailcontact">
                <input value=" name" size="25" id="contactname" type="text" name="name" onblur="if(this.value=='') this.value=' name';" onfocus="if(this.value==' name') this.value='';" /> 
                <input value=" email" size="25" id="contactemail" type="text" name="email" onblur="if(this.value=='') this.value=' email';" onfocus="if(this.value==' email') this.value='';" />
                <input value=" subject" size="25" id="contactsubject" type="text" name="subject" onblur="if(this.value=='') this.value=' subject';" onfocus="if(this.value==' subject') this.value='';" />
                <textarea name="message"> message</textarea>
                <input onclick="validate();return false;" value="validate_then_send" type="image" src="../images/sendbutton.png" style=" width: 200px; border: none; position: relative; left: 360px;" />
            </form>​
于 2012-10-10T20:36:26.663 回答