<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
html, body {
    margin: 0;
    font-size: 1.2em;
    overflow: scroll;
    -webkit-overflow-scrolling: touch;
}

#target {
    width: 2000px;
    height: 300px;
    background-color: gray;
}

code {
    color: green;
}
</style>

<div id="target"></div>
<img src="large-red-square.png"></img>

<script>
target.addEventListener("dragenter", event => event.preventDefault());
target.addEventListener("dragover", event => event.preventDefault());
target.addEventListener("drop", event => {
    target.innerHTML = "<code>PASS</code>";
    event.preventDefault();
});
</script>