How do I remove a file from the FileList

I'm building a drag-and-drop-to-upload web application using HTML5, and I'm dropping the files onto a div and of course fetching the dataTransfer object, which gives me the FileList.

Now I want to remove some of the files, but I don't know how, or if it's even possible.

Preferably I'd like to just delete them from the FileList; I've got no use for them. But if that's not possible, should I instead write in checks in code that interacts with the FileList? That seems cumbersome.

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If you want to delete only several of the selected files: you can't. The File API Working Draft you linked to contains a note:

The HTMLInputElement interface [HTML5] has a readonly FileList attribute, […]
[emphasis mine]

Reading a bit of the HTML 5 Working Draft, I came across the Common input element APIs. It appears you can delete the entire file list by setting the value property of the input object to an empty string, like:

document.getElementById('multifile').value = "";

BTW, the article Using files from web applications might also be of interest.

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This question has already been marked answered, but I'd like to share some information that might help others with using FileList.

It would be convenient to treat a FileList as an array, but methods like sort, shift, pop, and slice don't work. As others have suggested, you can copy the FileList to an array. However, rather than using a loop, there's a simple one line solution to handle this conversion.

 // fileDialog.files is a FileList 

 var fileBuffer=[];

 // append the file list to an array
 Array.prototype.push.apply( fileBuffer, fileDialog.files ); // <-- here

 // And now you may manipulated the result as required

 // shift an item off the array
 var file = fileBuffer.shift(0,1);  // <-- works as expected
 console.info( file.name + ", " + file.size + ", " + file.type );

 // sort files by size
 fileBuffer.sort(function(a,b) {
    return a.size > b.size ? 1 : a.size < b.size ? -1 : 0;
 });

Tested OK in FF, Chrome, and IE10+

---

Since we are in the HTML5 realm, this is my solution. The gist is that you push the files to an Array instead of leaving them in a FileList, then using XHR2, you push the files to a FormData object. Example below.

Node.prototype.replaceWith = function(node)
{
    this.parentNode.replaceChild(node, this);
};
if(window.File && window.FileList)
{
    var topicForm = document.getElementById("yourForm");
    topicForm.fileZone = document.getElementById("fileDropZoneElement");
    topicForm.fileZone.files = new Array();
    topicForm.fileZone.inputWindow = document.createElement("input");
    topicForm.fileZone.inputWindow.setAttribute("type", "file");
    topicForm.fileZone.inputWindow.setAttribute("multiple", "multiple");
    topicForm.onsubmit = function(event)
    {
        var request = new XMLHttpRequest();
        if(request.upload)
        {
            event.preventDefault();
            topicForm.ajax.value = "true";
            request.upload.onprogress = function(event)
            {
                var progress = event.loaded.toString() + " bytes transfered.";
                if(event.lengthComputable)
                progress = Math.round(event.loaded / event.total * 100).toString() + "%";
                topicForm.fileZone.innerHTML = progress.toString();
            };
            request.onload = function(event)
            {
                response = JSON.parse(request.responseText);
                // Handle the response here.
            };
            request.open(topicForm.method, topicForm.getAttribute("action"), true);
            var data = new FormData(topicForm);
            for(var i = 0, file; file = topicForm.fileZone.files[i]; i++)
                data.append("file" + i.toString(), file);
            request.send(data);
        }
    };
    topicForm.fileZone.firstChild.replaceWith(document.createTextNode("Drop files or click here."));
    var handleFiles = function(files)
    {
        for(var i = 0, file; file = files[i]; i++)
            topicForm.fileZone.files.push(file);
    };
    topicForm.fileZone.ondrop = function(event)
    {
        event.stopPropagation();
        event.preventDefault();
        handleFiles(event.dataTransfer.files);
    };
    topicForm.fileZone.inputWindow.onchange = function(event)
    {
        handleFiles(topicForm.fileZone.inputWindow.files);
    };
    topicForm.fileZone.ondragover = function(event)
    {
        event.stopPropagation();
        event.preventDefault();
    };
    topicForm.fileZone.onclick = function()
    {
        topicForm.fileZone.inputWindow.focus();
        topicForm.fileZone.inputWindow.click();
    };
}
else
    topicForm.fileZone.firstChild.replaceWith(document.createTextNode("It's time to update your browser."));

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