JavaScript，如何删除元素的值/内容/位？

Question

我需要发送文件，我想要拖放/删除 无需使用jQuery 然后，我尝试使用以下内容获取文件位，

<form action="https://cocacola.tld/index.php" enctype="multipart/form-data" method="post">

<input type="file" name="bitsfile" />

<div id="mydiv" contenteditable="true" ondrop="document.forms.bitsfile.value = BITS_from_this_DROPPED_element;">drag file here</div>

<hr /><input type="submit" />
</form>

但是“ bits_from_this_dropped_element”不起作用。

如何获得“二进制”或元素的值下降的值？

Answer 1

这可能会为您提供帮助：

<form action="https://cocacola.tld/index.php" enctype="multipart/form-data" method="post">

    <input type="text" name="bitsfile" id="bitsfile" />
    
    <div style="min-height: 100px;" id="mydiv" contenteditable="true" ondragenter="document.getElementById('bitsfile').value = ''; event.stopPropagation(); event.preventDefault();" ondragover="event.stopPropagation(); event.preventDefault();" ondrop="event.stopPropagation(); event.preventDefault(); dodrop(event);" >drag file here</div>
    
    <hr /><input type="submit" />
</form>

<script>
    function dodrop(event)
    {
        var dt = event.dataTransfer;
        var files = dt.files;

        var count = files.length;
        var temp = "File Count: " + count + "\n";
        var sumBits = 0;

        for (var i = 0; i < files.length; i++) {
            temp += " File " + i + ":\n(" + (typeof files[i]) + ") : <" + files[i] + " > " +
                files[i].name + " " + files[i].size + "\n";
            sumBits+= files[i].size;
        }
        document.getElementById('mydiv').innerText = temp;
        document.getElementById('bitsfile').value = sumBits;
    }

</script>

来源： https .org/en-us/doc/web/api/dataTransfer/files

Answer 2

“大技巧”是：

FileReader()

现在，如果您想要预览图像：

https://develoverer.mozilla.org/en-us/docs/web/web/api/filereader/readasdataurl