Javascript 为什么webpack加载多个app.js文件而不是单个app.js文件

我使用webpack创建了一个没有CLI的angular应用程序。一切正常。但当我调试它时，我发现我的app.js文件被多次加载

下面是我的webpack.config.js文件

const HtmlWebpackPlugin = require('html-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const ScriptExtPlugin = require('script-ext-html-webpack-plugin');
const { AngularCompilerPlugin } = require('@ngtools/webpack');
var path = require('path');

module.exports = function () {
    return {
        //entry: './src/main.ts',
        entry: {
            // vendor: './src/vendor.ts',
            polyfills: './src/polyfills.ts',
            main: './src/main.ts'
        },
        output: {
            path: __dirname + '/src',
            publicPath: "/",
            filename: 'app.js'
        },
        watch: true,
        resolve: {
            extensions: ['.ts', '.js']
        },
        devServer: {
            contentBase: path.join(__dirname, 'src'),
            watchContentBase: true,
            // hot: true,
        },
        module: {
            rules: [
                { test: /\.ts$/, loaders: ['awesome-typescript-loader', 'angular2-template-loader'] },
                {
                    test: /\.html$/,
                    loader: 'html-loader'
                }
            ]
        },
        plugins: [
            new CopyWebpackPlugin([
                { from: 'src/assets', to: 'assets' }
            ]),
            new HtmlWebpackPlugin({
                template: __dirname + '/src/index.html',
                output: __dirname + '/dist',
                inject: 'head'
            }),

            new ScriptExtPlugin({
                defaultAttribute: 'defer'
            }),
            new AngularCompilerPlugin({
                tsConfigPath: './tsconfig.json',
                entryModule: './src/app/app.module#AppModule',
                sourceMap: true
            })

        ]
    };
} 

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dirname的值是多少？在Node.js中，_dirname始终是当前正在执行的脚本所在的目录，无需声明