The simplest way to preload an image is to instantiate a new Image() object in JavaScript and pass it the URL of the image you want preloaded. Say we have an image called heavyimagefile.jpg, which ...

JavaScript Load Image is a library to load images provided as File or Blob objects or via URL. It returns an optionally scaled and/or cropped HTML img or canvas element via an asynchronous callback.

and image swaps. Keep following along as Thau gets down and dirty with the JavaScript Document Object Model, windows and frames, JavaScript syntax with loops, arrays, and functions, and forms.