webpack区分打包类库代码及hash优化

利用浏览器的缓存机制，减少服务器压力,合理使用缓存

使用new webpack.optimize.CommonsChunkPlugin时报错：Error: webpack.optimize.CommonsChunkPlugin has been removed, please use config.optimization.splitChunks instead.

解决方案
config.optimization = {
splitChunks: {
cacheGroups: {
commons: {
name: “vendor”,
chunks: “initial”,
minChunks: 2
}
}
}
}