統計資料

在使用 webpack 編譯原始碼時，使用者可以產生一個包含模組統計資料的 JSON 檔案。這些統計資料可用於分析應用程式的相依性圖表以及最佳化編譯速度。通常使用下列 CLI 指令產生檔案

npx webpack --profile --json=compilation-stats.json

--json=compilation-stats.json 旗標會指示 webpack 輸出包含相依性圖表和各種其他建置資訊的 compilation-stats.json。通常也會加入 --profile 旗標，以便在每個 modules 物件 中加入 profile 區段，其中包含特定模組的編譯統計資料。

結構

輸出 JSON 檔案的頂層結構相當直接，但也有少數巢狀資料結構。每個巢狀結構在下方都有專門的區段，以讓這份文件更容易閱讀。請注意，您可以按一下頂層結構中的連結，以跳到相關區段和文件

{
  "version": "5.9.0", // Version of webpack used for the compilation
  "hash": "11593e3b3ac85436984a", // Compilation specific hash
  "time": 2469, // Compilation time in milliseconds
  "publicPath": "auto",
  "outputPath": "/", // path to webpack output directory
  "assetsByChunkName": {
    // Chunk name to emitted asset(s) mapping
    "main": ["web.js?h=11593e3b3ac85436984a"],
    "named-chunk": ["named-chunk.web.js"],
    "other-chunk": ["other-chunk.js", "other-chunk.css"]
  },
  "assets": [
    // A list of asset objects
  ],
  "chunks": [
    // A list of chunk objects
  ],
  "modules": [
    // A list of module objects
  ],
  "entryPoints": {
    // A list of entry objects
  },
  "errors": [
    // A list of error objects
  ],
  "errorsCount": 0, // number of errors
  "warnings": [
    // A list of warning objects
  ],
  "warningsCount": 0 // nummber of warnings
}

資產物件

每個 assets 物件代表編譯產生的 output 檔案。它們都遵循類似的結構

{
  "chunkNames": [], // The chunks this asset contains
  "chunks": [10, 6], // The chunk IDs this asset contains
  "comparedForEmit": false, // Indicates whether or not the asset was compared with the same file on the output file system
  "emitted": true, // Indicates whether or not the asset made it to the `output` directory
  "name": "10.web.js", // The `output` filename
  "size": 1058, // The size of the file in bytes
  "info": {
    "immutable": true, // A flag telling whether the asset can be long term cached (contains a hash)
    "size": 1058, // The size in bytes, only becomes available after asset has been emitted
    "development": true, // A flag telling whether the asset is only used for development and doesn't count towards user-facing assets
    "hotModuleReplacement": true, // A flag telling whether the asset ships data for updating an existing application (HMR)
    "sourceFilename": "originalfile.js", // sourceFilename when asset was created from a source file (potentially transformed)
    "javascriptModule": true // true, when asset is javascript and an ESM
  }
}

區塊物件

每個 chunks 物件代表一組模組，稱為 區塊。每個物件遵循下列結構

{
  "entry": true, // Indicates whether or not the chunk contains the webpack runtime
  "files": [
    // An array of filename strings that contain this chunk
  ],
  "filteredModules": 0, // See the description in the [top-level structure](#structure) above
  "id": 0, // The ID of this chunk
  "initial": true, // Indicates whether this chunk is loaded on initial page load or [on demand](/guides/lazy-loading)
  "modules": [
    // A list of [module objects](#module-objects)
    "web.js?h=11593e3b3ac85436984a"
  ],
  "names": [
    // An list of chunk names contained within this chunk
  ],
  "origins": [
    // See the description below...
  ],
  "parents": [], // Parent chunk IDs
  "rendered": true, // Indicates whether or not the chunk went through Code Generation
  "size": 188057 // Chunk size in bytes
}

chunks 物件也會包含 origins 清單，描述給定區塊的來源。每個 origins 物件遵循下列架構

{
  "loc": "", // Lines of code that generated this chunk
  "module": "(webpack)\\test\\browsertest\\lib\\index.web.js", // Path to the module
  "moduleId": 0, // The ID of the module
  "moduleIdentifier": "(webpack)\\test\\browsertest\\lib\\index.web.js", // Path to the module
  "moduleName": "./lib/index.web.js", // Relative path to the module
  "name": "main", // The name of the chunk
  "reasons": [
    // A list of the same `reasons` found in [module objects](#module-objects)
  ]
}

模組物件

如果沒有編譯應用程式實際模組的一些說明，這些統計資料有什麼用？相依圖中的每個模組都由下列結構表示

{
  "assets": [
    // A list of [asset objects](#asset-objects)
  ],
  "built": true, // Indicates that the module went through [Loaders](/concepts/loaders), Parsing, and Code Generation
  "cacheable": true, // Whether or not this module is cacheable
  "chunks": [
    // IDs of chunks that contain this module
  ],
  "errors": 0, // Number of errors when resolving or processing the module
  "failed": false, // Whether or not compilation failed on this module
  "id": 0, // The ID of the module (analogous to [`module.id`](/api/module-variables/#moduleid-commonjs))
  "identifier": "(webpack)\\test\\browsertest\\lib\\index.web.js", // A unique ID used internally
  "name": "./lib/index.web.js", // Path to the actual file
  "optional": false, // All requests to this module are with `try... catch` blocks (irrelevant with ESM)
  "prefetched": false, // Indicates whether or not the module was [prefetched](/plugins/prefetch-plugin)
  "profile": {
    // Module specific compilation stats corresponding to the [`--profile` flag](/api/cli/#profiling) (in milliseconds)
    "building": 73, // Loading and parsing
    "dependencies": 242, // Building dependencies
    "factory": 11 // Resolving dependencies
  },
  "reasons": [
    // See the description below...
  ],
  "size": 3593, // Estimated size of the module in bytes
  "source": "// Should not break it...\r\nif(typeof...", // The stringified raw source
  "warnings": 0 // Number of warnings when resolving or processing the module
}

每個模組也包含 reasons 物件清單，說明該模組為何包含在相依圖中。每個「原因」類似於 區塊物件 區段中上面看到的 origins

{
  "loc": "33:24-93", // Lines of code that caused the module to be included
  "module": "./lib/index.web.js", // Relative path to the module based on [context](/configuration/entry-context/#context)
  "moduleId": 0, // The ID of the module
  "moduleIdentifier": "(webpack)\\test\\browsertest\\lib\\index.web.js", // Path to the module
  "moduleName": "./lib/index.web.js", // A more readable name for the module (used for "pretty-printing")
  "type": "require.context", // The [type of request](/api/module-methods) used
  "userRequest": "../../cases" // Raw string used for the `import` or `require` request
}

進入物件

"main": {
  "name": "main",
  "chunks": [
    179
  ],
  "assets": [
    {
      "name": "main.js",
      "size": 22
    }
  ],
  "filteredAssets": 0,
  "assetsSize": 22,
  "auxiliaryAssets": [],
  "filteredAuxiliaryAssets": 0,
  "auxiliaryAssetsSize": 0,
  "children": {},
  "childAssets": {},
  "isOverSizeLimit": false
}

錯誤和警告

errors 和 warnings 屬性各包含物件清單。每個物件包含訊息、堆疊追蹤和各種其他屬性

{
  "moduleIdentifier": "C:\\Repos\\webpack\\test\\cases\\context\\issue-5750\\index.js",
  "moduleName": "(webpack)/test/cases/context/issue-5750/index.js",
  "loc": "3:8-47",
  "message": "Critical dependency: Contexts can't use RegExps with the 'g' or 'y' flags.",
  "moduleId": 29595,
  "moduleTrace": [
    {
      "originIdentifier": "C:\\Repos\\webpack\\test\\cases|sync|/^\\.\\/[^/]+\\/[^/]+\\/index\\.js$/",
      "originName": "(webpack)/test/cases sync ^\\.\\/[^/]+\\/[^/]+\\/index\\.js$",
      "moduleIdentifier": "C:\\Repos\\webpack\\test\\cases\\context\\issue-5750\\index.js",
      "moduleName": "(webpack)/test/cases/context/issue-5750/index.js",
      "dependencies": [
        {
          "loc": "./context/issue-5750/index.js"
        }
      ],
      "originId": 32582,
      "moduleId": 29595
    },
    {
      "originIdentifier": "C:\\Repos\\webpack\\testCases.js",
      "originName": "(webpack)/testCases.js",
      "moduleIdentifier": "C:\\Repos\\webpack\\test\\cases|sync|/^\\.\\/[^/]+\\/[^/]+\\/index\\.js$/",
      "moduleName": "(webpack)/test/cases sync ^\\.\\/[^/]+\\/[^/]+\\/index\\.js$",
      "dependencies": [
        {
          "loc": "1:0-70"
        }
      ],
      "originId": 8198,
      "moduleId": 32582
    }
  ],
  "details": "at RequireContextDependency.getWarnings (C:\\Repos\\webpack\\lib\\dependencies\\ContextDependency.js:79:5)\n    at Compilation.reportDependencyErrorsAndWarnings (C:\\Repos\\webpack\\lib\\Compilation.js:1727:24)\n    at C:\\Repos\\webpack\\lib\\Compilation.js:1467:10\n    at _next2 (<anonymous>:16:1)\n    at eval (<anonymous>:42:1)\n    at C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2830:7\n    at Object.each (C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2850:39)\n    at C:\\Repos\\webpack\\lib\\FlagDependencyExportsPlugin.js:219:18\n    at C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2830:7\n    at Object.each (C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2850:39)\n    at C:\\Repos\\webpack\\lib\\FlagDependencyExportsPlugin.js:40:16\n    at Hook.eval [as callAsync] (<anonymous>:38:1)\n    at Hook.CALL_ASYNC_DELEGATE [as _callAsync] (C:\\Repos\\tapable\\lib\\Hook.js:18:14)\n    at Compilation.finish (C:\\Repos\\webpack\\lib\\Compilation.js:1462:28)\n    at C:\\Repos\\webpack\\lib\\Compiler.js:909:18\n    at processTicksAndRejections (internal/process/task_queues.js:75:11)\n",
  "stack": "ModuleDependencyWarning: Critical dependency: Contexts can't use RegExps with the 'g' or 'y' flags.\n    at Compilation.reportDependencyErrorsAndWarnings (C:\\Repos\\webpack\\lib\\Compilation.js:1732:23)\n    at C:\\Repos\\webpack\\lib\\Compilation.js:1467:10\n    at _next2 (<anonymous>:16:1)\n    at eval (<anonymous>:42:1)\n    at C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2830:7\n    at Object.each (C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2850:39)\n    at C:\\Repos\\webpack\\lib\\FlagDependencyExportsPlugin.js:219:18\n    at C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2830:7\n    at Object.each (C:\\Repos\\webpack\\node_modules\\neo-async\\async.js:2850:39)\n    at C:\\Repos\\webpack\\lib\\FlagDependencyExportsPlugin.js:40:16\n    at Hook.eval [as callAsync] (<anonymous>:38:1)\n    at Hook.CALL_ASYNC_DELEGATE [as _callAsync] (C:\\Repos\\tapable\\lib\\Hook.js:18:14)\n    at Compilation.finish (C:\\Repos\\webpack\\lib\\Compilation.js:1462:28)\n    at C:\\Repos\\webpack\\lib\\Compiler.js:909:18\n    at processTicksAndRejections (internal/process/task_queues.js:75:11)\n"
}