function clear() {
    var input = document.createElement("input");
    input.setAttribute('type', 'file');
    input.setAttribute('value', '');
    input.setAttribute('id', 'email_attach');

    $('#email_attach').replaceWith( input.cloneNode() );
}

在IE8中，为了安全起见，他们将文件上传字段设置为只读。查看IE团队的博客文章:

Historically, the HTML File Upload Control () has been the source of a significant number of information disclosure vulnerabilities. To resolve these issues, two changes were made to the behavior of the control. To block attacks that rely on “stealing” keystrokes to surreptitiously trick the user into typing a local file path into the control, the File Path edit box is now read-only. The user must explicitly select a file for upload using the File Browse dialog. Additionally, the “Include local directory path when uploading files” URLAction has been set to "Disable" for the Internet Zone. This change prevents leakage of potentially sensitive local file-system information to the Internet. For instance, rather than submitting the full path C:\users\ericlaw\documents\secret\image.png, Internet Explorer 8 will now submit only the filename image.png.

什么? 在验证函数中

document.onlyform.upload.value="";

假设upload是名称:

<input type="file" name="upload" id="csv_doc"/>

我使用JSP，不确定这是否有区别…

对我来说是可行的，而且我觉得这样简单多了。

我一直在寻找简单而干净的方法来清除HTML文件输入，上面的答案是伟大的，但没有一个真正回答我在寻找什么，直到我在网络上遇到了一个简单而优雅的方法来做到这一点:

var $input = $("#control");

$input.replaceWith($input.val('').clone(true));

这一切都要归功于克里斯·科伊尔。

// Referneces var control = $("#control"), clearBn = $("#clear"); // Setup the clear functionality clearBn.on("click", function(){ control.replaceWith( control.val('').clone( true ) ); }); // Some bound handlers to preserve when cloning control.on({ change: function(){ console.log( "Changed" ) }, focus: function(){ console.log( "Focus" ) } }); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="file" id="control"> <br><br> <a href="#" id="clear">Clear</a>

最后我得出了这个结论:

if($.browser.msie || $.browser.webkit){
  // doesn't work with opera and FF
  $(this).after($(this).clone(true)).remove();  
}else{
  this.setAttribute('type', 'text');
  this.setAttribute('type', 'file'); 
}

也许不是最优雅的解决方案，但据我所知它很有效。

一个简单的方法是改变输入类型，然后再把它改回来。

就像这样:

var input = $('#attachments');
input.prop('type', 'text');
input.prop('type', 'file')