dev.config.js

var port = 3000;
module.exports = {
    entry: [
        //'webpack-dev-server/client?http://localhost:' + port,
        "./src/Index.js"
    ],
    output: {
        filename: "./build/bundle.js"
    },
    module: {
        rules: [{
            test: /\.(css|scss)$/,
            use: [{
                loader: "style-loader" // creates style nodes from JS strings
            }, {
                loader: "css-loader" // translates CSS into CommonJS
            }, {
                loader: "sass-loader" // compiles Sass to CSS
            }]
        },{
            test: /\.js$/,
            exclude: /node_modules/,
            use: {
                loader: 'babel-loader',
                options: {
                    presets: ['env', 'es2015','react','stage-0']
                }
            }
        },{
            test : /\.(eot|otf|woff|woff2|ttf|svg|jpg|jpeg|png|gif)(\?\S*)?$/,
            loader: 'file-loader?name=/[path][name].[ext]',
        }]
    },
    devServer: {
        contentBase: './',
        watchContentBase: true,
        port: port,
        inline: true,
        headers: {
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Credentials": "true",
            "Access-Control-Allow-Headers": "Content-Type, Authorization, x-id, Content-Length, X-Requested-With",
            "Access-Control-Allow-Methods": "GET, POST, PUT, DELETE, OPTIONS"
        }
    }
}