Get Attribute for image

getting attr without ID

HTML

<script src="http://4.bp.blogspot.com/-uyvTMZ3dFPs/UKHsc_ZbysI/AAAAAAAACvo/QdVAlVBbUxE/s320/1hello.jpg"></script>
<img src="http://4.bp.blogspot.com/-uyvTMZ3dFPs/UKHsc_ZbysI/AAAAAAAACvo/QdVAlVBbUxE/s320/1hello.jpg" width='400' height='400' alt='Sample_image' onclick='imageInfo(this.src);'>

JavaScript

window.imageInfo = function (source) {
    alert('image');
    alert(source);
}