Atlas.js | simple game engine worked on canvas elements | Game Engine library

I am using Electron framework in node.js to create a HTML5 Canvas game, I have mapped all of my resources into Atlases (one image containing sprites). Before the game is starting I want to load every atlas.pngs into an object that continues to map all the atlases together so it is easier to use the images in the canvas element.

While doing this in Electron I was unable to freeze the Electron BrowserWindow. This makes my application/game just continue the code, or sometimes it stops.