ladybird/Tests/LibWeb/Text/input/FileAPI/filereader-basic.html

<script src="../include.js"></script>
<script>
    asyncTest((done) => {
        const array = ['This is some data to be read! 🦬'];
        let blob = new Blob(array, { type: "application/octet-stream"});
        let fileReader = new FileReader();

        let count = 0;

        // Trigger events in order of readAs Text->DataURL->ArrayBuffer
        fileReader.addEventListener("loadend", () => {
            ++count;

            if (count === 1) {
                println(`${count}: readAsText(): '${fileReader.result}' error: '${fileReader.error}'`);
                fileReader.readAsDataURL(blob);
            } else if (count === 2) {
                println(`${count}: readAsDataURL(): '${fileReader.result}' error: '${fileReader.error}'`);
                fileReader.readAsArrayBuffer(blob);
            } else if (count === 3) {
                println(`${count}: readAsArrayBuffer(): '${new TextDecoder().decode(fileReader.result)}' error: '${fileReader.error}'`);
                done();
            }
        });

        fileReader.readAsText(blob);
    });
</script>