procedure TForm1.WebFilePicker1Change(Sender: TObject);
begin
  if WebFilePicker1.Files.Count > 0 then
    WebFilePicker1.Files[0].GetAsArrayBuffer;
end;

procedure TForm1.WebFilePicker1GetFileAsArrayBuffer(Sender: TObject; AFileIndex: Integer; ABuffer: TJSArrayBufferRecord);
begin
  WebZip1.Open(ABuffer);
end;

procedure TForm1.WebZip1ZipLoaded(Sender: TObject);
begin
  //This is the implementation of the OnZipLoaded event:
  //here we know that the ZIP was successfully opened
  //and we can proceed with related calculations/tasks
end;

WebZip1.Add('subfolder/sub.txt', 'I''m in a subfolder!'); //Add sub.txt in the 'subfolder' folder
WebZip1.Add('hello.txt', 'Hello World'); //Adds hello.txt to the ZIP and sets the content to 'Hello World'
WebZip1.Add('hello.txt', 'Hello ZIP'); //Overrides the content of hello.txt

WebZip1.ReadAsString('hello.txt', procedure(AFileName, AData: string)
begin
  //process AData here
end);

WebZip1.Remove('hello.txt'); //removes hello.txt from ZIP
WebZip1.RemoveAll; //removes all of the files from the ZIP

WebZip1.Download('myzip.zip', zcStore); //no compression
WebZip1.Download('myzip.zip', zcDeflateLevel1); //best speed
WebZip1.Download('myzip.zip', zcDeflateLevel9); //best compression

procedure TForm1.WebZip1Progress(Sender: TObject; APercent: Single; ACurrentFile: string);
begin
  WebProgressBar1.Position := Round(APercent);
end;