【注意】最后更新于 December 3, 2019,文中内容可能已过时,请谨慎使用。
使用ajax上传文件的时候为了通过 files
api来获取文件信息,从而可以看到显示进度
html
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<div class="row">
<label for="file">
Upload Image:</label>
<input type="file" name="fileToUpload" id="fileToUpload" multiple="multiple" onchange="fileSelected();" />
</div>
<div id="fileName">
</div>
<div id="fileSize">
</div>
<div id="fileType">
</div>
<div class="row">
<input type="button" onclick="uploadFile()" value="Upload Image" />
</div>
<div id="progressNumber">
</div>
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js
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function fileSelected() {
var file = document.getElementById('fileToUpload').files[0];
if (file) {
var fileSize = 0;
if (file.size > 1024 * 1024)
fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';
else
fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';
document.getElementById('fileName').innerHTML = 'Name: ' + file.name;
document.getElementById('fileSize').innerHTML = 'Size: ' + fileSize;
document.getElementById('fileType').innerHTML = 'Type: ' + file.type;
}
}
function uploadFile() {
var fd = new FormData();
fd.append("fileToUpload", document.getElementById('fileToUpload').files[0]);
var xhr = new XMLHttpRequest();
xhr.upload.addEventListener("progress", uploadProgress, false);
xhr.addEventListener("load", uploadComplete, false);
xhr.addEventListener("error", uploadFailed, false);
xhr.addEventListener("abort", uploadCanceled, false);
xhr.open("POST", "Home/Upload");
xhr.send(fd);
}
function uploadProgress(evt) {
if (evt.lengthComputable) {
var percentComplete = Math.round(evt.loaded * 100 / evt.total);
document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';
}
else {
document.getElementById('progressNumber').innerHTML = 'unable to compute';
}
}
function uploadComplete(evt) {
/* This event is raised when the server send back a response */
alert(evt.target.responseText);
}
function uploadFailed(evt) {
alert("There was an error attempting to upload the file.");
}
function uploadCanceled(evt) {
alert("The upload has been canceled by the user or the browser dropped the connection.");
}
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这里加了一个监听事件,可以通过异步来不断获取上传信息,从而能正常的显示上传进度
文章来源
另一个资料-使用 JavaScript File API 实现文件上传
文章作者
GPF
上次更新
2019-12-03
(2587928)