convert image sequence to avi with ffmpeg

convert.js

var PREFIX = 'c' + Math.floor(Math.random() * 1000) + '-',
	EXTENSION = 'bmp',
	ROOT_DIR = '',
	FFMPEG_PATH = 'ffmpeg-20151116-git-1fe82ab-win64-static\\bin\\ffmpeg.exe',
	FFMPEG_ARGS = '-framerate 30',
	FILE_OUTPUT = 'test.avi'

var app = WScript.CreateObject('Shell.Application'),
	shell = WScript.CreateObject('WScript.Shell'),
	fso = WScript.CreateObject('Scripting.FileSystemObject')


var folder = app.BrowseForFolder(0, 'Select the folder for the images', 0, ROOT_DIR)
if (!folder) WScript.Quit()

// what the hell 'Self' is?
var folderPath = folder.Self.Path,
	files = fso.getFolder(folderPath).Files,
	names = [ ]
for (var i = new Enumerator(files); !i.atEnd(); i.moveNext()) {
	var path = '' + i.item(),
		name = path.split('\\').pop(),
		suffix = name.split('.').pop()
	if (suffix === EXTENSION)
		names.push(name)
}


var selected = shell.Popup('Continue with ' + names.length + ' files?', 0, 'Warning', 1)
if (selected === 2) WScript.Quit()

var ffmpeg = shell.CurrentDirectory + '\\' + FFMPEG_PATH
shell.CurrentDirectory = folderPath
names = names.sort()
for (var i = 0; i < names.length; i ++) {
	var index = (i + 1e9 + '').slice(-9)
	fso.MoveFile(names[i], PREFIX + index + '.' + EXTENSION)
}

var cmd = '"' + ffmpeg + '" -i "' + PREFIX + '%09d.' + EXTENSION + '" ' +
	FFMPEG_ARGS + ' -y ' + FILE_OUTPUT
shell.Run(cmd, 1, true)