如何基于addEventListener ass触发器将两个几乎相同的javascript函数写为一个

Question

我今天大部分时间都在思考这个问题。我有两种触发同一事件的方法。1.通过单击输入：文件选择器，或2.通过将文件拖放到"dropzone"中

事件之间的唯一区别是文件API使用不同的方法。eventListeners函数调用中似乎只允许使用（event）参数。我可能错过了什么，但任何帮助都非常感谢

但仅仅复制粘贴几乎相同的代码确实很烦人。有没有办法把这两个函数"fileSelect（event）和dropSelect（event）"合为一？

代码：

function fileSelect(event){
    event.stopPropagation();
    event.preventDefault();
    selectedFile = event.target.files[0];       //Uses ".files" from the file API in HTML5. In this case accessing info on a single file (files[0]).
    //Insert file info
    document.getElementById('filename').innerHTML = "filename: " + selectedFile.name;
    document.getElementById('filetype').innerHTML = "filetype: " + selectedFile.type;
    document.getElementById('filesize').innerHTML = "filesize: " + parseFloat(selectedFile.size/1024).toFixed(1) + " kb";
}
//parse the info from a drag'n'drop-selected image. WRITE THESE 2 FUNCTIONS INTO ONE!
function dropSelect(event){
    event.stopPropagation();
    event.preventDefault();
    selectedFile = event.dataTransfer.files[0];     //Uses ".files" from the file API in HTML5. In this case accessing info on a single file (files[0]).
    //Insert file info
    document.getElementById('filename').innerHTML = "filename: " + selectedFile.name;
    document.getElementById('filetype').innerHTML = "filetype: " + selectedFile.type;
    document.getElementById('filesize').innerHTML = "filesize: " + parseFloat(selectedFile.size/1024).toFixed(1) + " kb";
}


//add onchange event to the file_select input:file. This will run function "fileSelect", onChange. 
document.getElementById('file_select').addEventListener('change', fileSelect, false);
//start fileselect when drag'n'drop.
function handleDragOver(event){
    event.stopPropagation();
    event.preventDefault();
    event.dataTransfer.dropEffect = 'copy';
}
document.getElementById('upload_box').addEventListener('dragover', handleDragOver, false);
document.getElementById('upload_box').addEventListener('drop', dropSelect, false);

Answer 1

function select(event){
    event.stopPropagation();
    event.preventDefault();
    selectedFile = (event.dataTransfer || event.target).files[0];
    //Insert file info
    document.getElementById('filename').innerHTML = "filename: " + selectedFile.name;
    document.getElementById('filetype').innerHTML = "filetype: " + selectedFile.type;
    document.getElementById('filesize').innerHTML = "filesize: " + parseFloat(selectedFile.size/1024).toFixed(1) + " kb";
}

Answer 2

考虑通用代码：

function insertFileInfo(file) {
    //Insert file info
    document.getElementById('filename').innerHTML = "filename: " + file.name;
    document.getElementById('filetype').innerHTML = "filetype: " + file.type;
    document.getElementById('filesize').innerHTML = "filesize: " + parseFloat(file.size/1024).toFixed(1) + " kb";
}
function fileSelect(event){
    event.stopPropagation();
    event.preventDefault();
    insertFileInfo(event.target.files[0]);
}
function dropSelect(event){
    event.stopPropagation();
    event.preventDefault();
    insertFileInfo(event.dataTransfer.files[0]);
}

Answer 3

这可能有效@andreas代码的更改selectedFile=（event.dataTransfer || event.target）.files[0]；

至

selectedFile = (event.dataTransfer ? event.dataTransfer.files[0] : event.target.files[0]);