based on: https://twitter.com/jobertabma/status/920840311890255873

js_extract.js

#!/bin/env node
// https://gist.github.com/cedriczirtacic

var argv = process.argv;
if (argv.length < 3) {
    console.info("%s <url>", argv[1]);
    process.exit(1);
}

var url = argv[2];
var http_options = {}
var http;
var r;

if (( r = /^(https*):\/\/(.+?)(?:([0-9]+))?(\/.+)$/gi.exec(url))) {
    http = require(r[1]);
    if (r[3] != undefined) {
        http_options.port = r[3];
    }
    http_options.host = r[2];
    http_options.path = r[4];
} else {
    console.error("error: bad url (\"%s\")", url);
    process.exit(2);
}

var url_parse = /(?:url\:["'](.+?)['"]|load\(["'](.+?)['"]\)|(?:\(|=|:)\s*['"](\/*[\/%\w\d=_\.\-]+(\.[\w]*)\??)+)/gmi;
let http_data = '';
http.get(http_options, (res) => {
    if (res.statusCode != 200){
        console.error("error: status code %d", res.statusCode);
        process.exitCode = 1;
        return false;
    }
    res.on('data', (data) => {
            if (r[3] == "https")
                http_data += data.text;
            else
                http_data += data;
        })
        .on('end', () => {
            http_data = http_data.replace(/(;|\{|\})+/g, "$1\n");
            var parsed_data;
            while (parsed_data = url_parse.exec(http_data)){
                var path;
                if (parsed_data[1] == undefined)
                    path = parsed_data[0];
                else
                    path = parsed_data[1];
                path = path.replace(/^(?:[\(=:]["'])/g, '');
                //if (!/^\//.test(path))
                //    path = "/"+path;
                console.info(path);
            }
        });
}).on('error', (error) => {
    console.error(error.message);
});