ladybird/Tests/LibWeb/Text/input/HTML/data-transfer.html

<script src="../include.js"></script>
<script>
    test(() => {
        let dataTransfer = new DataTransfer();
        println(`dropEffect: ${dataTransfer.dropEffect}`);
        println(`effectAllowed: ${dataTransfer.effectAllowed}`);

        let dataTransferItemList = dataTransfer.items;

        let stringItem = dataTransferItemList.add("well hello friends", "custom-type");
        println(`stringItem: ${stringItem}, types=${dataTransfer.types}`);

        try {
            dataTransferItemList.add("well hello friends", "custom-type");
            println("FAILED");
        } catch (e) {}

        let file = new File(["well hello friends"], "file.txt", {
            type: "text/plain",
        });

        let fileItem = dataTransferItemList.add(file);
        println(`fileItem: ${fileItem}, types=${dataTransfer.types}`);
    });
</script>