javascript - 应用 javascript 检查文件大小和扩展名

Question

这是我的脚本。我想要做的是使用 onchange 事件触发它。但似乎效果不是很好。我试过在这里和那里编辑，但仍然面临问题。至于我在下面的最新编辑，问题是，有 2 个文件要上传，但只有第二个会显示警告消息，而第一个只会收到任何文件。

    <script>
    function checkFile()
    {   
    var node_list = document.getElementsByTagName('input');
    for (var i = 0; i < node_list.length; i++) 
    {
        var node = node_list[i];
        if (node.getAttribute('type') == 'file') 
        {
            var sFileName = node.value;
            var sFileExtension = sFileName.split('.')[sFileName.split('.').length - 1];
            var iFileSize = node.files[0].size;
            var iConvert=(node.files[0].size/10485760).toFixed(2);
        }


        if (sFileExtension != "pdf" && sFileExtension != "doc" && sFileExtension != "docx" && iFileSize>10485760)
        {   
            txt="File type : "+ sFileExtension+"\n\n";
            txt+="Size: " + iConvert + " MB \n\n";
            txt+="Please make sure your file is in pdf or doc format and less than 10 MB.\n\n";
            alert(txt);
        }
    }
}
    </script>

我的表格，

  <input type="file" name="file" id="confirm" onchange="checkFile()">
  <input type="file" name="file" id="approveletter" onchange="checkFile()">

Answer 1

与其依赖元素本身，不如使用函数的给定事件来获取触发回调函数调用的文件。

传入事件将保证您实际上正在处理导致函数被调用的当前文件。

例如(我更改了变量名以使其更清楚):

ONLINE DEMO HERE

/// pass in event 
function checkFile(e) {

    /// get list of files
    var file_list = e.target.files;

    /// go through the list of files
    for (var i = 0, file; file = file_list[i]; i++) {

        var sFileName = file.name;
        var sFileExtension = sFileName.split('.')[sFileName.split('.').length - 1].toLowerCase();
        var iFileSize = file.size;
        var iConvert = (file.size / 1048576).toFixed(2);

        /// OR together the accepted extensions and NOT it. Then OR the size cond.
        /// It's easier to see this way, but just a suggestion - no requirement.
        if (!(sFileExtension === "pdf" ||
              sFileExtension === "doc" ||
              sFileExtension === "docx") || iFileSize > 10485760) { /// 10 mb
            txt = "File type : " + sFileExtension + "\n\n";
            txt += "Size: " + iConvert + " MB \n\n";
            txt += "Please make sure your file is in pdf or doc format and less than 10 MB.\n\n";
            alert(txt);
        }
    }
}