ADDED - better support for per-route static file serving https://github.com/BrowserSync/browser-sync/commit/97dd9071cadf6f753563e5f69ea5e8efa9b6cbd9 For example, let's say you have a deployed Wordpress website at http://example.com where the assets live inside wp-content/themes/awesome/. Now lets imagine you need to make small CSS tweaks in style.css, but you don't want the hassle of running PHP + MySQL on your local machine... With Browsersync you can now easily map remote paths to local ones. So if you have the file wp-content/themes/awesome/style.css on your machine, you could run the following and have your changes update the live website.

/**
* This example will proxy an EXISTING website
* whilst serving assets from your local directory.
* This is crazy-powerful, especially when you consider
* it works across all devices.
*/
const bs = require('browser-sync').create();

bs.init({
    proxy: 'http://example.com',
    files: ['htdocs/wp-content/themes/awesome'], // watch files
    serveStatic: [
        {
            route: '/wp-content/themes/awesome',     // remote path
            dir: 'htdocs/wp-content/themes/awesome'  // local path
        }
    ]
});

This kind of magic was always possible with Browsersync, but it required more complicated setup that we're happy to see the back of. The best bit is that the proxy will kick in if a file is not found locally. So in our Wordpress example, you could have nothing but a CSS file and everything would still work.

A knock-on effect of this feature is that now you can map multiple remote paths to multiple local directories... I know, it's magical and amazing.

// map 2 remote paths to 1 local directory
serveStatic: [
    {
        route: ['/wp-content/themes/theme1', '/wp-content/themes/theme2'],
        dir: './my-local'  // local path
    }
]

// map 1 remote path to 2 local directories
serveStatic: [
    {
        route: '/wp-content/themes/theme1',
        dir: ['./my-local', './tmp']  // local path
    }
]

ADDED support for opening browsers with flags** https://github.com/BrowserSync/browser-sync/pull/1179

For example, if you wanted to open Chrome with certain flags when Browsersync starts, you can do

const bs = require('browser-sync').create();

bs.init({
server: './app',
browser: [
    {
        app: [
            'chromium-browser',
            '--app=http://localhost:8080',
            '--proxy-server=localhost:8080',
            '--user-data-dir=.tmp/chomium'
        ]
    }
]
});

This can also be combined with the string-only versions too - so to open chrome with flags, but safari + firefox as normal:

const bs = require('browser-sync').create();

bs.init({
server: './app',
browser: [
    {
        app: [
            'chromium-browser',
            '--app=http://localhost:8080',
            '--proxy-server=localhost:8080',
            '--user-data-dir=.tmp/chomium'
        ]
    },
    'safari',
    'firefox'
]
});