jQuery Pjax
pushState + ajax = pjax
Java Script Load Image
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. It also provides a method to parse image meta data to extract Exif tags and thumbnails and to restore the complete image header after resizing.
Nanobar
Very lightweight progress bars. No jQuery
Layzr.js
A small, fast, modern, and dependency-free library for lazy loading.
Head js
The only script in your HEAD. Head JS loads JavaScript files in parallel like images without blocking the page. Your page will be faster. Even with a single combined file.
LABjs
Loading And Blocking JavaScript: On-demand parallel loader for JavaScript with execution order dependencies