<!DOCTYPE html
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>如何用HTML5的FileReader生成Data Url</title>
<meta name="keywords" content="Data Url,HTML5,FileReader"/>
<meta name="description" content="如何用HTML5的FileReader生成Data Url"/>
<script type="text/javascript">
function buildDataUrl(source) {
var file = source.files[0];
if(window.FileReader) {
var fr = new FileReader();
fr.onloadend = function(e) {
document.getElementById("txtBase64").value = e.target.result; document.getElementById("imgView").src = e.target.result; };
fr.readAsDataURL(file); }
}
</script>
</head>
<body>
<p>如何用HTML5的FileReader生成Data Url</p>
<input type="file" value="" onchange="buildDataUrl(this)" style="border:1px solid #808080; width:300px;" /><br />
<textarea id="txtBase64" cols="50" rows="20"></textarea>
<img id="imgView" src="" style="width:300px;" />
</body>
</html>
原文：http://blog.csdn.net/html5_/article/details/46574705