<DOCTYPE !html>
<html>
<head>
<meta charset="utf8">
<meta name="viewport" content="width=device-width">
<style>
    body {
        width: 100%;
        height: 100%;
        margin: 0;
    }

    #source, #destination {
        width: 200px;
        height: 200px;
    }

    #destination {
        border: red 1px solid;
    }
</style>
<script>
    function runTest() {
        destination.addEventListener("dragenter", event => event.preventDefault());
        destination.addEventListener("dragover", event => event.preventDefault());
        destination.addEventListener("drop", event => {
            filecount.textContent = event.dataTransfer.files.length;
            destination.setAttribute("src", URL.createObjectURL(event.dataTransfer.files[0]));
            event.preventDefault();
        });
    }

    function destinationLoaded() {
        imageload.textContent = "true";
        imageload.style.color = "green";
    }
</script>
</head>
<body onload="runTest()">
    <div><img id="source" src="icon.png"></img></div>
    <img onload="destinationLoaded()" src="" id="destination"></img>
    <div id="output">
        <div>Number of files: <span id="filecount">N/A</span></div>
        <div>Image loaded? <span style="color: red" id="imageload">false</span></div>
    </div>
</body>
</html>