HTML5 File API始终返回[object file]的DataURI。我究竟做错了什么？ [英] HTML5 File API always returns DataURI of [object file]. What am I doing wrong?
本文介绍了HTML5 File API始终返回[object file]的DataURI。我究竟做错了什么？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
今天我一直试图制作一个使用拖放和文件API的缩略图加载器。
Today I have been attempting to make a thumbnail up loader which uses drag and drop and the file API.
我觉得好像我已经相当远了。但是作为我的图像文件中的源提供的DataURI总是作为[目标文件]返回，因此不显示图像。
I feel as if i have got reasonably far. But the DataURI that is provided to be the source in my image file ALWAYS returns as [object file] and therefore doesn't show the image.
任何帮助？！
谢谢。
Danny
Thanks. Danny
（以下是我的代码）
<!DOCTYPE html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style>
#thumbnailPreview
{
width:149px;
height:137px;
border:3px dashed #333;
border-radius:10px;
text-align:center;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>
<script>
$("document").ready(function() {
if (!!FileReader)
{
$("#thumbnailPreview").append("<p>Drag image here to set as thumbnail</p>")
$("#thumbnailUploadBox").hide();
var thumbnailPreview = document.getElementById("thumbnailPreview")
// init event handlers
thumbnailPreview.addEventListener("dragenter", preventDefault, false);
thumbnailPreview.addEventListener("dragexit", preventDefault, false);
thumbnailPreview.addEventListener("dragover", preventDefault, false);
thumbnailPreview.addEventListener("drop", drop, false)
function preventDefault(evt)
{
evt.stopPropagation();
evt.preventDefault();
}
function drop(evt)
{
evt.stopPropagation();
evt.preventDefault();
var files = evt.dataTransfer.files;
var noOfFiles = files.length;
if (noOfFiles === 1)
{
handleImages(files);
}
else
{
alert("You appear to be attempting to upload more or less than 1 image. You can only have one thumbnail image. Please try again.");
}
}
function handleImages(files)
{
var file = files[0];
{
if(file.type.indexOf("image") == 0)
{
$("#thumbnailPreview").empty().append('<p>Working on it!</p><progress id="progressbar"></progress>');
var reader = new FileReader();
reader.onloadend = handleReaderLoadEnd;
reader.onprogress = handleReaderProgress;
reader.readAsDataURL(file);
}
else
{
alert("The file you dragged wasn't an image. Please drag another file before attempting to upload");
}
}
}
function handleReaderLoadEnd(e) {
$("#thumbnailPreview").empty().prepend('<img id="thumbnailPreviewImage">');
$("#thumbnailPreviewImage").attr({src: e.target.result});
}
function handleReaderProgress(evt)
{
if (evt.lengthComputable)
{
var loaded = (evt.loaded / evt.total);
$("#progressbar").attr({ value: loaded * 100 });
}
}
}
});
</script>
</head>
<body>
<form action="lighthouseMaker.php" enctype="application/x-www-form-urlencoded" method="post">
<div id="thumbnailPreview">
<p>Upload an Image 149 x 137px</p>
</div>
<div id="thumbnailUploadBox">
<input type="file" name="thumbnail">
</div>
</form>
</body>
</html>
推荐答案
您正在设置FileReader的 onloadend 处理程序返回值 handleReaderLoadEnd（）而不是设置回调并传递ecent。相反，你想要：
You're setting the FileReader's onloadend handler to the return value of handleReaderLoadEnd() rather than setting the callback and it passing the ecent. Instead, you want:
reader.onloadend = handleReaderLoadEnd;
....
function handleReaderLoadEnd(e) {
$("#thumbnailPreview").empty().prepend('<img id="thumbnailPreviewImage">');
$("#thumbnailPreviewImage").attr({src: e.target.result});
}
这篇关于HTML5 File API始终返回[object file]的DataURI。我究竟做错了什么？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
