本文实例讲述了JS+html5实现异步上传图片显示上传文件进度条功能。分享给大家供大家参考，具体如下：
<html>
<head>
</head>
<body>
<p>
emo_album_id:<input type="text" name="emo_album_id" id="emo_album_id" value='1'>
</p>
<p>
name:<input type="text" name="title" id="title">
</p>
<div class="row">
<label for="file">
Upload Image:</label>
<input type="file" name="fileToUpload" id="fileToUpload" multiple="multiple" onchange="fileSelected();" />
</div>
SentenceMovie[photo]
<div id="fileName">
</div>
<div id="fileSize">
</div>
<div id="fileType">
</div>
<div id="progressNumber">
</div>
<script>
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;
uploadFile();
}
}
function uploadFile() {
var fd = new FormData();
fd.append("upload_file", document.getElementById('fileToUpload').files[0]);
fd.append("emo_album_id", document.getElementById('emo_album_id').value);
fd.append("title", document.getElementById('title').value);
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", "http://mysae.com/emotions/1/api/index.php/emo/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.");
}
</script>
</body>
</html>