样例
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
function gen_base64() {
var file = document.getElementById('upload_file').files[0];
r = new FileReader(); //本地预览
r.onload = function() {
console.log(r.result);
document.getElementById('base64_output').value = r.result;
document.getElementById('myImg').src = r.result;
}
r.readAsDataURL(file); //Base64
}
</script>
</head>
<body>
<input accept="image/*" name="upimage" id="upload_file" type="file" onchange="gen_base64()">
<br />
<textarea id="base64_output" name="Word" style=" width:820px"></textarea>
<br />
<img src="" id="myImg" />
</body>
</html>
