是否有可能清除<input type='file' />控件值与jQuery?我试过以下几种方法:

$('#control').attr({ value: '' }); 

但这并不奏效。


当前回答

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.

其他回答

我使用了https://github.com/malsup/form/blob/master/jquery.form.js,它有一个名为clearInputs()的函数,它是跨浏览器的,经过良好测试,易于使用,并在需要时处理IE问题和隐藏字段清除。也许这个解决方案有点长,只清除文件输入,但如果你正在处理跨浏览器的文件上传,那么这个解决方案是推荐的。

用法简单:

// Clear all file fields:
$("input:file").clearInputs();

// Clear also hidden fields:
$("input:file").clearInputs(true);

// Clear specific fields:
$("#myfilefield1,#myfilefield2").clearInputs();
/**
 * Clears the selected form elements.
 */
$.fn.clearFields = $.fn.clearInputs = function(includeHidden) {
    var re = /^(?:color|date|datetime|email|month|number|password|range|search|tel|text|time|url|week)$/i; // 'hidden' is not in this list
    return this.each(function() {
        var t = this.type, tag = this.tagName.toLowerCase();
        if (re.test(t) || tag == 'textarea') {
            this.value = '';
        }
        else if (t == 'checkbox' || t == 'radio') {
            this.checked = false;
        }
        else if (tag == 'select') {
            this.selectedIndex = -1;
        }
        else if (t == "file") {
            if (/MSIE/.test(navigator.userAgent)) {
                $(this).replaceWith($(this).clone(true));
            } else {
                $(this).val('');
            }
        }
        else if (includeHidden) {
            // includeHidden can be the value true, or it can be a selector string
            // indicating a special test; for example:
            //  $('#myForm').clearForm('.special:hidden')
            // the above would clean hidden inputs that have the class of 'special'
            if ( (includeHidden === true && /hidden/.test(t)) ||
                 (typeof includeHidden == 'string' && $(this).is(includeHidden)) )
                this.value = '';
        }
    });
};

Jquery应该为你解决跨浏览器/旧浏览器的问题。

这适用于我测试的现代浏览器:Chromium v25、Firefox v20、Opera v12.14

使用jquery 1.9.1

HTML

<input id="fileopen" type="file" value="" />
<button id="clear">Clear</button>

Jquery

$("#clear").click(function () {
    $("#fileopen").val("");
});

据jsfiddle

下面的javascript解决方案也适用于我上面提到的浏览器。

document.getElementById("clear").addEventListener("click", function () {
    document.getElementById("fileopen").value = "";
}, false);

据jsfiddle

I have no way to test with IE, but theoretically this should work. If IE is different enough that the Javascript version does not work because MS have done it in a different way, the jquery method should in my opinion deal with it for you, else it would be worth pointing it out to the jquery team along with the method that IE requires. (I see people saying "this won't work on IE", but no vanilla javascript to show how it does work on IE (supposedly a "security feature"?), perhaps report it as a bug to MS too (if they would count it as such), so that it gets fixed in any newer release)

就像在jquery论坛的另一个帖子中提到的

 if ($.browser.msie) {
      $('#file').replaceWith($('#file').clone());
 } else {
      $('#file').val('');
 }

但是jquery现在已经删除了对浏览器测试的支持。

这个javascript解决方案也为我工作,它是香草的jquery等价。replaceWith方法。

document.getElementById("clear").addEventListener("click", function () {
    var fileopen = document.getElementById("fileopen"),
        clone = fileopen.cloneNode(true);

    fileopen.parentNode.replaceChild(clone, fileopen);
}, false);

据jsfiddle

需要注意的重要一点是,cloneNode方法不保存相关的事件处理程序。

请看这个例子。

document.getElementById("fileopen").addEventListener("change", function () {
    alert("change");
}, false);

document.getElementById("clear").addEventListener("click", function () {
    var fileopen = document.getElementById("fileopen"),
        clone = fileopen.cloneNode(true);

    fileopen.parentNode.replaceChild(clone, fileopen);
}, false);

据jsfiddle

但是jquery。克隆提供[*1]

$("#fileopen").change(function () {
    alert("change");
});

$("#clear").click(function () {
    var fileopen = $("#fileopen"),
        clone = fileopen.clone(true);

    fileopen.replaceWith(clone);
});

据jsfiddle

[*1]如果事件是由jquery的方法添加的,jquery能够做到这一点,因为它在jquery中保留了一个副本。数据,否则它不能工作,所以这是一种欺骗/变通,意味着不同方法或库之间不兼容。

document.getElementById("fileopen").addEventListener("change", function () {
    alert("change");
}, false);

$("#clear").click(function () {
    var fileopen = $("#fileopen"),
        clone = fileopen.clone(true);

    fileopen.replaceWith(clone);
});

据jsfiddle

您不能直接从元素本身获得附加的事件处理程序。

这是在香草javascript的一般原则,这是如何jquery和所有其他库做的(粗略)。

(function () {
    var listeners = [];

    function getListeners(node) {
        var length = listeners.length,
            i = 0,
            result = [],
            listener;

        while (i < length) {
            listener = listeners[i];
            if (listener.node === node) {
                result.push(listener);
            }

            i += 1;
        }

        return result;
    }

    function addEventListener(node, type, handler) {
        listeners.push({
            "node": node,
                "type": type,
                "handler": handler
        });

        node.addEventListener(type, handler, false);
    }

    function cloneNode(node, deep, withEvents) {
        var clone = node.cloneNode(deep),
            attached,
            length,
            evt,
            i = 0;

        if (withEvents) {
            attached = getListeners(node);
            if (attached) {
                length = attached.length;
                while (i < length) {
                    evt = attached[i];
                    addEventListener(clone, evt.type, evt.handler);

                    i += 1;
                }
            }
        }

        return clone;
    }

    addEventListener(document.getElementById("fileopen"), "change", function () {
        alert("change");
    });

    addEventListener(document.getElementById("clear"), "click", function () {
        var fileopen = document.getElementById("fileopen"),
            clone = cloneNode(fileopen, true, true);

        fileopen.parentNode.replaceChild(clone, fileopen);
    });
}());

据jsfiddle

当然,jquery和其他库有维护这样一个列表所需的所有其他支持方法,这只是一个演示。

我已经设法让这个工作使用以下…

function resetFileElement(ele) 
{
    ele.val(''); 
    ele.wrap('<form>').parent('form').trigger('reset');   
    ele.unwrap();
    ele.prop('files')[0] = null;
    ele.replaceWith(ele.clone());    
}

这已在IE10, FF, Chrome和Opera测试。

有两点需要注意……

在FF中仍然不能正常工作,如果您刷新页面,文件元素将使用所选文件重新填充。我不知道它是从哪里得到这些信息的。还有什么与文件输入元素相关,我可以尝试清除? 记住对附加到文件输入元素的任何事件使用委托,这样它们在克隆时仍然有效。

我不明白的是,到底是谁认为不允许您从无效的不可接受的文件选择中清除输入字段是一个好主意?

不要让我动态地设置它的值这样我就不能从用户的操作系统中窃取文件,但是我可以在不重置整个表单的情况下清除无效的选择。

它不像'accept'做任何事情,除了一个过滤器,无论如何,在IE10,它甚至不理解微软Word mime类型,这是一个笑话!

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。

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>