Webpack 4迁移CommonsChunkPlugin

Question

我需要帮助将以下代码从webpack 3迁移到4。

new webpack.optimize.CommonsChunkPlugin({
    minChunks: module => module.context && module.context.indexOf("node_modules") !== -1,
    name: "vendor",
    chunks: ["main"]
})

我有两个条目文件，并且只希望第一个条目的依赖项包含在供应商块中。第二个条目的依赖项都应该保留在它自己的包中。

Answer 1

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我们已经弃用并删除了CommonsChunkPlugin，取而代之的是一组名为optimization.splitChunks的默认值和易于覆盖的接口。

webpack.optimize.CommonsChunkPlugin has been removed, 
please use config.optimization.splitChunks instead.

已弃用

您不再需要使用这些插件：

DedupePlugin has been removed too in v4

NoEmitOnErrorsPlugin optimization.noEmitOnErrors (生产模式下默认打开) NamedModulesPlugin -> optimization.noEmitOnErrors(生产模式下默认打开)NamedModulesPlugin -> optimization.namedModules (开发模式下默认打开)

​

对webpack 4的推荐

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使用mini-css-extract-plugin而不是text-extract-plugin。使用webpack-bundle-analyzer以图形方式分析捆绑的输出。

入口脚本对于你的应用程序来说是真正的“入口脚本”，不要在webpack.config.js中显式地将供应商文件添加到entry:中。SPA应用程序有一个入口和多页面-像经典的ASP.NET MVC应用程序一样有多个入口点。Webpack将从你的入口脚本中构建依赖图，并为你的应用程序生成优化的捆绑包。

如果您想要从较早的webpack版本迁移，最好是签出migration guide

树抖动(死码消除)仅在生产模式下启用。

Webpack 4，捆绑资产的新方式

(你必须将你的CommonsChunkPlugin-thinking从你的头脑中移除)

!!! Meanwhile the webpack doc has been updated, a section SplitChunks was added !!!

It follows a new philosophy

现在，默认情况下，Webpack 4会自动执行优化。它会分析您的依赖关系图，并基于以下条件创建最佳包(输出)：

1. 可以共享新块或者模块来自node_modules文件夹
2. 新块将大于30kb (在min+gz之前)
3. 按需加载块时的最大并行请求数<= 5
4. 初始页面加载时的最大并行请求数<= 3

所有这些都可以使用SplitChunksPlugin！(see SplitChunksPlugin documentation)进行调整。

A more detailed explanation，了解如何使用新的optimization.splitChunks应用编程接口。

CommonsChunkPlugin被删除，因为它有很多问题：

• 它会导致下载的代码比所需的代码多。
• 它对异步区块的效率很低。
• 它很难使用。
• 实现很难理解。

SplitChunksPlugin还有一些很棒的属性：

• 它从不下载不需要的模块(只要您不通过名称执行区块合并)
• 它在异步区块上的工作效率也很高
• 对于异步区块它是默认启用的
• 它可以处理多个供应商区块的供应商拆分
• 它更易于使用
• 它不依赖于区块图hacks
• 大部分是自动的

--> Source

关于您的问题，您希望将entry1和entry2的所有部门拆分成单独的捆绑包。

      optimization: {
        splitChunks: {
          cacheGroups: {   
            "entry1-bundle": {
              test: /.../,   // <-- use the test property to specify which deps go here
              chunks: "all",
              name: "entry1-bundle",
 /** Ignore minimum size, minimum chunks and maximum requests and always create chunks for this cache group */
              enforce: true,
              priority: ..  // use the priority, to tell where a shared dep should go
            },
            "entry2-bundle": {
              test: /..../, // <-- use the test property to specify which deps go here
              chunks: "all",
              name: "entry2-bundle",
              enforce: true,
              priority: ..
            }
          }
        }
      },

如果不添加优化：follows条目，则 如下所示

splitChunks: {
  chunks: 'async',
  minSize: 30000,
  minRemainingSize: 0,
  maxSize: 0,
  minChunks: 1,
  maxAsyncRequests: 6,
  maxInitialRequests: 4,
  automaticNameDelimiter: '~',
  automaticNameMaxLength: 30,
  cacheGroups: {
    vendors: {
      test: /[\\/]node_modules[\\/]/,
      priority: -10
    },
    default: {
      minChunks: 2,
      priority: -20,
      reuseExistingChunk: true
    }
  }
}

您可以将optimization.splitChunks.cacheGroups.default设置为false以禁用默认缓存组，vendors缓存组也是如此！

下面是其他一些SplitChunks configuration examples的解释。

​

SplitChunksOptions、CachGroupOptions和Optimization的最新接口实现可以在here上找到。

​

下面的接口定义可能不是100%准确的，但对于简单的概述是很好的：

SplitChunksOptions 接口

interface SplitChunksOptions {
    /** Select chunks for determining shared modules (defaults to \"async\", \"initial\" and \"all\" requires adding these chunks to the HTML) */
    chunks?: "initial" | "async" | "all" | ((chunk: compilation.Chunk) => boolean);
    /** Minimal size for the created chunk */
    minSize?: number;
    /** Minimum number of times a module has to be duplicated until it's considered for splitting */
    minChunks?: number;
    /** Maximum number of requests which are accepted for on-demand loading */
    maxAsyncRequests?: number;
    /** Maximum number of initial chunks which are accepted for an entry point */
    maxInitialRequests?: number;
    /** Give chunks created a name (chunks with equal name are merged) */
    name?: boolean | string | ((...args: any[]) => any);
    /** Assign modules to a cache group (modules from different cache groups are tried to keep in separate chunks) */
    cacheGroups?: false | string | ((...args: any[]) => any) | RegExp | { [key: string]: CacheGroupsOptions };
}

CacheGroupsOptions interface:

interface CacheGroupsOptions {
    /** Assign modules to a cache group */
    test?: ((...args: any[]) => boolean) | string | RegExp;
    /** Select chunks for determining cache group content (defaults to \"initial\", \"initial\" and \"all\" requires adding these chunks to the HTML) */
    chunks?: "initial" | "async" | "all" | ((chunk: compilation.Chunk) => boolean);
    /** Ignore minimum size, minimum chunks and maximum requests and always create chunks for this cache group */
    enforce?: boolean;
    /** Priority of this cache group */
    priority?: number;
    /** Minimal size for the created chunk */
    minSize?: number;
    /** Minimum number of times a module has to be duplicated until it's considered for splitting */
    minChunks?: number;
    /** Maximum number of requests which are accepted for on-demand loading */
    maxAsyncRequests?: number;
    /** Maximum number of initial chunks which are accepted for an entry point */
    maxInitialRequests?: number;
    /** Try to reuse existing chunk (with name) when it has matching modules */
    reuseExistingChunk?: boolean;
    /** Give chunks created a name (chunks with equal name are merged) */
    name?: boolean | string | ((...args: any[]) => any);
}

Optimization 接口

interface Optimization {
    /**
     *  Modules are removed from chunks when they are already available in all parent chunk groups.
     *  This reduces asset size. Smaller assets also result in faster builds since less code generation has to be performed.
     */
    removeAvailableModules?: boolean;
    /** Empty chunks are removed. This reduces load in filesystem and results in faster builds. */
    removeEmptyChunks?: boolean;
    /** Equal chunks are merged. This results in less code generation and faster builds. */
    mergeDuplicateChunks?: boolean;
    /** Chunks which are subsets of other chunks are determined and flagged in a way that subsets don’t have to be loaded when the bigger chunk has been loaded. */
    flagIncludedChunks?: boolean;
    /** Give more often used ids smaller (shorter) values. */
    occurrenceOrder?: boolean;
    /** Determine exports for each module when possible. This information is used by other optimizations or code generation. I. e. to generate more efficient code for export * from. */
    providedExports?: boolean;
    /**
     *  Determine used exports for each module. This depends on optimization.providedExports. This information is used by other optimizations or code generation.
     *  I. e. exports are not generated for unused exports, export names are mangled to single char identifiers when all usages are compatible.
     *  DCE in minimizers will benefit from this and can remove unused exports.
     */
    usedExports?: boolean;
    /**
     *  Recognise the sideEffects flag in package.json or rules to eliminate modules. This depends on optimization.providedExports and optimization.usedExports.
     *  These dependencies have a cost, but eliminating modules has positive impact on performance because of less code generation. It depends on your codebase.
     *  Try it for possible performance wins.
     */
    sideEffects?: boolean;
    /** Tries to find segments of the module graph which can be safely concatenated into a single module. Depends on optimization.providedExports and optimization.usedExports. */
    concatenateModules?: boolean;
    /** Finds modules which are shared between chunk and splits them into separate chunks to reduce duplication or separate vendor modules from application modules. */
    splitChunks?: SplitChunksOptions | false;
    /** Create a separate chunk for the webpack runtime code and chunk hash maps. This chunk should be inlined into the HTML */
    runtimeChunk?: boolean | "single" | "multiple" | RuntimeChunkOptions;
    /** Avoid emitting assets when errors occur. */
    noEmitOnErrors?: boolean;
    /** Instead of numeric ids, give modules readable names for better debugging. */
    namedModules?: boolean;
    /** Instead of numeric ids, give chunks readable names for better debugging. */
    namedChunks?: boolean;
    /** Defines the process.env.NODE_ENV constant to a compile-time-constant value. This allows to remove development only code from code. */
    nodeEnv?: string | false;
    /** Use the minimizer (optimization.minimizer, by default uglify-js) to minimize output assets. */
    minimize?: boolean;
    /** Minimizer(s) to use for minimizing the output */
    minimizer?: Array<Plugin | Tapable.Plugin>;
    /** Generate records with relative paths to be able to move the context folder". */
    portableRecords?: boolean;
}
}

Answer 2

我有两个入口文件，并且只希望第一个入口文件的依赖项包含在供应商块中。第二个条目的依赖项都应该保留在它自己的包中。

假设入口点是main和secondary

entry: {
    main: 'path-to/main.js',
    secondary: 'path-to/secondary.js'
}

使用webpack-4，您可以只从main块中提取vendors模块，而使用您想要创建的cacheGroups的test函数将secondary中引用的其他第三方模块保留在该块中。

optimization: {
    splitChunks: {
        cacheGroups: {
            vendors: {
                name: 'vendors',
                chunks: 'all',
                reuseExistingChunk: true,
                priority: 1,
                enforce: true,
                test(module, chunks) {
                    const name = module.nameForCondition && module.nameForCondition();
                    return chunks.some(chunk => {
                        return chunk.name === 'main' && /[\\/]node_modules[\\/]/.test(name);
                    });
                }
            },
            secondary: {
                name: 'secondary',
                chunks: 'all',
                priority: 2,
                enforce: true,
                test(module, chunks) {
                    return chunks.some(chunk => chunk.name === 'secondary');
                }
            }
        }
    }
}

Answer 3

我花了一段时间才明白这一点，但对我来说关键的认识是，webpack 4中的chunks参数现在接受一个函数，它允许您只包含一个特定的条目。我假设这是一个最近的变化，因为在发帖的时候，官方文档中没有它。

splitChunks: {
  cacheGroups: {
    vendor: {
      name: 'vendor',
      chunks: chunk => chunk.name == 'main',
      reuseExistingChunk: true,
      priority: 1,
      test: module =>
        /[\\/]node_modules[\\/]/.test(module.context),
      minChunks: 1,
      minSize: 0,
    },
  },
},