var path = require("path");
module.exports = {
 entry:{
 app:["./app/main.js"]
 },
 output:{
 path:path.resolve(__dirname,"build"),
 publicPath:"/assets/",
 filename:"bundle.js"
}
}

webpack-dev-server --content-base build/

 var config = require("./webpack.config.js");
 var webpack = require('webpack');
 var WebpackDevServer = require('webpack-dev-server');

config.entry.app.unshift("webpack-dev-server/client?http://localhost:8080/");

var compiler = webpack(config);
var server = new WebpackDevServer(compiler, {
 contentBase:'build/',
 publicPath: "/assets/"
});
server.listen(8080);

webpack-dev-server --content-base build --inline --hot

var WebpackDevServer = require("webpack-dev-server");
var webpack = require("webpack");

var compiler = webpack({
 // configuration
});
var server = new WebpackDevServer(compiler, {
 // webpack-dev-server options

 contentBase: "/path/to/directory",
 // Can also be an array, or: contentBase: "http://localhost/",

 hot: true,
 // Enable special support for Hot Module Replacement
 // Page is no longer updated, but a "webpackHotUpdate" message is send to the content
 // Use "webpack/hot/dev-server" as additional module in your entry point
 // Note: this does _not_ add the `HotModuleReplacementPlugin` like the CLI option does. 

 // Set this as true if you want to access dev server from arbitrary url.
 // This is handy if you are using a html5 router.
 historyApiFallback: false,

 // Set this if you want to enable gzip compression for assets
 compress: true,

 // Set this if you want webpack-dev-server to delegate a single path to an arbitrary server.
 // Use "**" to proxy all paths to the specified server.
 // This is useful if you want to get rid of 'http://localhost:8080/' in script[src],
 // and has many other use cases (see https://github.com/webpack/webpack-dev-server/pull/127 ).
 proxy: {
 "**": "http://localhost:9090"
 },

 setup: function(app) {
 // Here you can access the Express app object and add your own custom middleware to it.
 // For example, to define custom handlers for some paths:
 // app.get('/some/path', function(req, res) {
 // res.json({ custom: 'response' });
 // });
 },

 // pass [static options](http://expressjs.com/en/4x/api.html#express.static) to inner express server
 staticOptions: {
 },

 // webpack-dev-middleware options
 quiet: false,
 noInfo: false,
 lazy: true,
 filename: "bundle.js",
 watchOptions: {
 aggregateTimeout: 300,
 poll: 1000
 },
 // It's a required option.
 publicPath: "/assets/",
 headers: { "X-Custom-Header": "yes" },
 stats: { colors: true }
});
server.listen(8080, "localhost", function() {});
// server.close();