preload.coffee

images = [
    'http://cdn.discogs.com/yqU-8wqol13SCGfPg2sYy9gBjb4=/100x100/filters:strip_icc():format(jpeg):mode_rgb()/discogs-images/R-3996200-1351777283-1914.jpeg.jpg',
    'http://cdn.discogs.com/U2oncEZe50hAlYSoFbVOkIf1Y0s=/fit-in/300x300/filters:strip_icc():format(jpeg):mode_rgb()/discogs-images/R-3578188-1440480186-6359.jpeg.jpg'
]

_preload = (src)->
    new Promise (resolve, reject)->
        image = document.createElement 'img'
        image.src = src
        image.onload = -> resolve image
        image.style.display = 'none'
        document.body.appendChild image
        setTimeout reject, 30000

render = (images)->
    # show something using all images

preload = (images)->
    Promise.all (_preload src for src in images)


preload(images).then render