HTML的JavaScript类型=文件

Question

随着HTML类型=文件，如何可以进行验证，以确定（使用JavaScript或jquery的用于客户端验证）

<form action="program" enctype="multipart/form-data" method="post"> 
<input type="text" name="textline" size="30"> 
<input type="file" name="datafile"> 
<input type="submit" value="Send"> 
</form> 

<script> 
if (something) 
    message = "You did not upload a file..."; 
</script>   

Answer 1

相同的方式，任何其它的输入，如果一个文件被上传， ，看看value。例如

<form id="programform" action="program" enctype=... 

<script type="text/javascript"> 
    document.getElementById('programform').onsubmit= function() { 
     if (this.elements.textline.value==='') 
      alert('Please enter a description.'); 
     if (this.elements.datafile.value==='') 
      alert('Please choose a file to upload.'); 
     else 
      return true; 
     return false; 
    } 
</script> 

Answer 2

感谢您在正确的方向推动......这就是我一直在寻找的东西。

<form name="registration_2" id="registration_b" action="registration_b.php" method="post" nctype="multipart/form-data" accept-charset="UTF-8" onsubmit="return check_checkboxes();"> 
<input type="text" name="textline" id="textline" size="30"> 
<input type="file" name="datafile" id="school_logo_id"> 
<input name="no_school_logo_id" id="no_school_logo_id" type="checkbox" onclick="no_school_logo(this);"/>Our school does not have a logo 
<input type="submit" value="Send"> 
</form> 



<script type="text/javascript"> 
function check_checkboxes() 
{ 
    var logo = document.getElementById('school_logo_id'); 
    var nologo = document.getElementById('no_school_logo_id'); 

     if (logo.value==='' && nologo.checked===false) 
      alert('Must enter logo file or check no file available.');   

} 
</script>