Read ANSI files in Web file-system-access API

I am trying to get files using file-system-access API and it works good using this code:

function Process_Files(files) {
    [].map.call(files, async function (file, i) {
        if (isDataFile(file.name)) {
            let fileText = await file.text();
            let filePath = await file.webkitRelativePath;
            ProcessFileContents(await fileText,await filePath);
        }
    })
}
function DirectoryChose(event) {

    let files;
    event.stopPropagation();
    event.preventDefault();


    if (event.type === "change") {
        files = event.target.files;
    }

    if (files) {
        Process_Files(files)
    }
}

dropArea.addEventListener("change", DirectoryChose);

the problem is when we have an ANSI encoded file then the German Characters like Ö, Ü, and Ä become � while it works perfect with UTF-8 encoded files.

I couldn't find anyway to read files using file.text() in ANSI code

thanks for help

You need to use the FileReader() API with the correct encoding. See the MDN docs for details. For example, you could read the data as below:

// fileOrBlob is a File or a Blob :-) 
const fileReader = new FileReader();
fileReader.readAsText(fileOrBlob, 'windows-1252');

The only thing to note is that you need to know the encoding beforehand. If you don't specify an encoding, UTF-8 is assumed.