extract-text-webpack-plugin" loader is used without the corresponding plugin How to deal

I made a mistake,

 plugins: [new webpack.HotModuleReplacementPlugin(), new webpack.ProvidePlugin({
        "React": "react",
        "ReactDOM": "react-dom",
        "_": "lodash",
        "classnames":"classnames"
    },new ExtractTextPlugin ("style.css",{allChunks: true}))

correct code

    plugins: [new webpack.HotModuleReplacementPlugin(), new webpack.ProvidePlugin({
        "React": "react",
        "ReactDOM": "react-dom",
        "_": "lodash",
        "classnames":"classnames"
    }),new ExtractTextPlugin("[name].css",{allChunks: true})
    ]