我有以下放置区,用户可以在其中选择图像或将图像拖到放置区。
当我通过input type=file
按钮选择文件并单击btnUpload
按钮时,图像即被上传。但是,当我将项目拖到放置区,然后单击btnUpload
按钮时,什么也没发生:没有日志记录,没有网络请求,什么也没有。
为什么?这是我的代码。
<div id="drop-area">
<span id="status"></span>
<p>Drop files here</p>
<input type="file" id="fileElem" multiple accept="image/*" onchange="handleFiles(this.files)">
<label class="button" for="fileElem">Select files</label>
<progress id="progress-bar" max=100 value=0></progress>
<div id="gallery" /></div>
<input id="btnUpload" type="submit" class="button green small" value="Upload" />
<script type="text/javascript">
let btnUpload = document.getElementById("btnUpload")
btnUpload.addEventListener('click',uploadFiles,false)
function uploadFiles(event) {
event.preventDefault();
// TODO - validate file size,extension & amount
files = [...fileElem.files]
// Submit each file separately.
files.forEach(uploadFile)
//check if success and if so,remove from gallery
}
// This all copy & paste
// ************************ Drag and drop ***************** //
let dropArea = document.getElementById("drop-area")
// Prevent default drag behaviors
;['dragenter','dragover','dragleave','drop'].forEach(eventName => {
dropArea.addEventListener(eventName,preventDefaults,false)
document.body.addEventListener(eventName,false)
})
// Highlight drop area when item is dragged over it
;['dragenter','dragover'].forEach(eventName => {
dropArea.addEventListener(eventName,highlight,false)
})
;['dragleave',unhighlight,false)
})
// Handle dropped files
dropArea.addEventListener('drop',handleDrop,false)
function preventDefaults(e) {
e.preventDefault()
e.stopPropagation()
}
function highlight(e) {
dropArea.classList.add('highlight')
}
function unhighlight(e) {
dropArea.classList.remove('active')
}
function handleDrop(e) {
var dt = e.dataTransfer
var files = dt.files
handleFiles(files)
}
let uploadProgress = []
let progressBar = document.getElementById('progress-bar')
function initializeProgress(numFiles) {
progressBar.value = 0
uploadProgress = []
for (let i = numFiles; i > 0; i--) {
uploadProgress.push(0)
}
}
function updateProgress(fileNumber,percent) {
uploadProgress[fileNumber] = percent
let total = uploadProgress.reduce((tot,curr) => tot + curr,0) / uploadProgress.length
//console.log('update',fileNumber,percent,total)
progressBar.value = total
return total === 100;
}
function handleFiles(files) {
files = [...files]
initializeProgress(files.length)
//files.forEach(uploadFile)
files.forEach(previewFile)
}
function previewFile(file) {
//console.error('file.name: ' + file.name);
let reader = new FileReader()
reader.readAsDataURL(file)
reader.onloadend = function () {
let img = document.createElement('img')
img.id = file.name;//.toString().replaceAll('"','').replaceAll('.','').replaceAll(' ','_');
img.src = reader.result
document.getElementById('gallery').appendChild(img)
}
}
function uploadFile(file,i) {
var url = '/api2/uploadfile/135/3435' // TODO: change end point
var xhr = new XMLHttpRequest()
var formData = new FormData()
xhr.open('POST',url,true)
xhr.setRequestHeader('X-Requested-With','XMLHttpRequest')
// Update progress (can be used to show progress indicator)
xhr.upload.addEventListener("progress",function (e) {
updateProgress(i,(e.loaded * 100.0 / e.total) || 100)
})
xhr.addEventListener('readystatechange',function (e) {
if (xhr.readyState == 4 && xhr.status == 200) {
if (updateProgress(i,100)) {
//$("'" + "#gallery #" + xhr.responseText.replaceAll('"','_') + "'").remove();//how do we handle spaces in filenames?
//console.error(i);
$('#gallery img:nth-child(' + (i + 1) + ')').hide();
//alert('Complete') // TODO
return true;
}
}
else if (xhr.readyState == 4 && xhr.status != 200) {
$('#status').html(GetMessageStatus('Error: ' + xhr.responseText,1));
return false;
}
})
formData.append('file',file)
xhr.send(formData)
}
</script>
更新1
我在这里添加了我的代码:https://plnkr.co/edit/HHPDL6Ndc6nxPMGn?open=lib%2Fscript.js
我调试了所有内容,并执行了相同的路径。但是,当我通过按钮选择1张图片并点击上载按钮时,在函数uploadFiles中,在files = [...fileElem.files]
的这一行中,变量files
的长度为1,但是当我拖放同一张图片并点击上传按钮,变量files
的长度为0。