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<script type="text/javascript">
function showImage(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$('#preview').attr('src', e.target.result);
}
reader.readAsDataURL(input.files[0]);
}
}
</script>
<body>
<form id="imageForm" runat="server">
<input type='file' onchange="showImage(this);" />
<img id="preview" src="#" alt="selected image" />
</form>
</body>
Learn more about previewing an image before and after upload.