Get file name and file contents as Byte Array

function getFileContentsAndMetadata(entityID) {
    // Get the name of the selected file
    var fileName = encodeURIComponent(document.getElementById('file-upload').files[0].name);
    // Get the content of the selected file
    var file = document.getElementById('file-upload').files[0];
    // If the user has selected a file
    if (file) {
        // Read the file as a byte array
        var reader = new FileReader();
        reader.readAsArrayBuffer(file);
        // The browser has finished reading the file, we can now do something with it...
        reader.onload = function(e) {
            // The browser has finished reading the file, we can now do something with it...
            var fileContent = e.target.result;
            // Run the function to upload to the Portal Web API, passing the GUID of the newly created record and the file's contents and name as inputs
            uploadFile(fileContent,fileName,entityID);
        };
    }
}