Progressbar modal

progress.js

let documentWindow = NSApplication.sharedApplication().mainWindow()

let mySheetWindow = NSWindow.alloc().initWithContentRect_styleMask_backing_defer(
    NSMakeRect(0, 0, 300, 50),
    (NSWindowStyleMaskTitled | NSWindowStyleMaskDocModalWindow),
    NSBackingStoreBuffered,
    true
)
let progressView = NSProgressIndicator
    .alloc()
    .initWithFrame(NSMakeRect(20, 20, 260, 12))
progressView.setControlTint(NSBlueControlTint)
progressView.startAnimation(true)
mySheetWindow.contentView().addSubview(progressView)

documentWindow.beginSheet_completionHandler(mySheetWindow, nil)

// put your long running code here
// once its done executing
// close the sheet

setTimeout(function() {
    documentWindow.endSheet(mySheetWindow)
}, 1000 * 3)