Scan a directory and create a JSON object of images (and write it to a file) of all the images in that directory.

create_images_json_object_from_dir.js

var sys = require("sys"),
    fs = require("fs");

function processImageDir(path, outFilename, cb) {
    fs.readdir(path, function(err, files) {

        var imgfiles = [];

        // Check for images and push on the array if it's a match.
        files.forEach(function(name) {
            name.substr(-4).match(/(png|jpeg|jpg|gif)/) && imgfiles.push(name)
        });

        fs.writeFile(__dirname + '/' + outFilename, JSON.stringify({
            images: imgfiles
        }), function(err) {
            if (err) throw err;
            cb && cb("Sweet.");
        });

    });
}

processImageDir('/path/to/your/images/dir', "preload-images.json", function(message) {
    console.log(message);
});