Core Plugins

Relevant source files

• packages/vite/src/node/__tests__/plugins/define.spec.ts
• packages/vite/src/node/__tests__/plugins/fixtures/oxc-tsconfigs/decorator-metadata/tsconfig.json
• packages/vite/src/node/__tests__/plugins/oxc.spec.ts
• packages/vite/src/node/plugins/asset.ts
• packages/vite/src/node/plugins/css.ts
• packages/vite/src/node/plugins/define.ts
• packages/vite/src/node/plugins/dynamicImportVars.ts
• packages/vite/src/node/plugins/html.ts
• packages/vite/src/node/plugins/importAnalysis.ts
• packages/vite/src/node/plugins/importAnalysisBuild.ts
• packages/vite/src/node/plugins/importMetaGlob.ts
• packages/vite/src/node/plugins/json.ts
• packages/vite/src/node/plugins/modulePreloadPolyfill.ts
• packages/vite/src/node/plugins/oxc.ts
• packages/vite/src/node/plugins/wasm.ts
• packages/vite/src/node/plugins/worker.ts
• packages/vite/src/node/server/middlewares/indexHtml.ts
• playground/define/__tests__/define.spec.ts
• playground/define/commonjs-dep/index.js
• playground/define/index.html
• playground/define/optional-env.js
• playground/define/vite.config.js
• playground/env/.env
• playground/env/__tests__/env.spec.ts
• playground/env/index.html
• playground/env/index.js
• playground/env/vite.config.js
• playground/glob-import/__tests__/glob-import.spec.ts
• playground/glob-import/external/x.js
• playground/glob-import/external/y.js
• playground/glob-import/root/index.html
• playground/js-sourcemap/__tests__/js-sourcemap.spec.ts

Core plugins are Vite's built-in plugins that handle essential transformations and processing during both development and build. These plugins implement fundamental features such as module resolution, CSS processing, HTML transformation, asset handling, and import analysis. They are automatically included in every Vite project and execute in a specific order as part of the plugin pipeline.

For information about the plugin API and hook system that core plugins use, see Plugin API and Hooks. For guidance on writing custom plugins, see Creating Custom Plugins.

Plugin Pipeline Organization

Core plugins are organized into execution tiers. User plugins can position themselves relative to core plugins using the enforce option. In Vite 8, many core transformation tasks are offloaded to native implementations in Rolldown/Oxc for performance.

Sources: packages/vite/src/node/plugins/importAnalysis.ts:80-81(), packages/vite/src/node/plugins/worker.ts:187-210()

Core Plugin Categories

Resolution Plugins

These plugins handle module resolution and aliasing, translating import specifiers to file paths.

Plugin	Purpose	Key Files
preAliasPlugin	Early alias resolution for optimized dependencies	packages/vite/src/node/plugins/preAlias.ts1-142
resolvePlugin	Main module resolver for bare imports, relative paths, and URLs	packages/vite/src/node/plugins/resolve.ts168-953

Sources: packages/vite/src/node/plugins/importAnalysis.ts:77-80()

Transform Plugins

Transform plugins process source code, converting between formats and applying optimizations. Vite 8 defaults to oxc for JS/TS/JSX transformations when bundled.

Plugin	Purpose	Implementation
oxcPlugin	Fast TS/JSX transformation via Oxc	packages/vite/src/node/plugins/oxc.ts210-245
jsonPlugin	Loads JSON files as ES modules	packages/vite/src/node/plugins/json.ts1-68
wasmPlugin	Handles .wasm file imports	packages/vite/src/node/plugins/wasm.ts1-124
cssPlugin	Processes CSS, preprocessors, and PostCSS	packages/vite/src/node/plugins/css.ts295-452
definePlugin	Replaces global constants (e.g. process.env.NODE_ENV)	packages/vite/src/node/plugins/define.ts12-165
importGlobPlugin	Handles import.meta.glob patterns	packages/vite/src/node/plugins/importMetaGlob.ts37-127

Sources: packages/vite/src/node/plugins/oxc.ts:210-245(), packages/vite/src/node/plugins/css.ts:1-294(), packages/vite/src/node/plugins/define.ts:12-165(), packages/vite/src/node/plugins/importMetaGlob.ts:44-55()

Asset and Worker Plugins

These plugins manage static assets and web workers.

Plugin	Purpose	Features
assetPlugin	Handles static asset imports with hashing and inlining	packages/vite/src/node/plugins/asset.ts152-163
webWorkerPlugin	Bundles web workers separately	packages/vite/src/node/plugins/worker.ts162-230
htmlInlineProxyPlugin	Proxies inline scripts and styles in HTML	packages/vite/src/node/plugins/html.ts103-137

Sources: packages/vite/src/node/plugins/asset.ts:152-225(), packages/vite/src/node/plugins/worker.ts:154-160(), packages/vite/src/node/plugins/html.ts:103-137()

Major Core Plugins

resolvePlugin

The resolve plugin implements Vite's module resolution algorithm. It is responsible for mapping browser-friendly specifiers to actual file system paths.

Resolution Logic:

1. Optimized Dependencies: Checks if the ID belongs to a pre-bundled dependency.
2. File System Paths: Handles /@fs/ prefixes for absolute paths.
3. Node Resolution: Uses Node's resolution algorithm (including exports and imports fields) for bare module specifiers.

Sources: packages/vite/src/node/plugins/importAnalysis.ts:108-145()

cssPlugin and cssPostPlugin

Vite provides first-class support for CSS, including preprocessors and CSS Modules.

cssPlugin Implementation Details:

• Preprocessors: Supports Sass, Less, and Stylus. Preprocessors can run in worker pools via WorkerWithFallback to avoid blocking the main thread packages/vite/src/node/plugins/css.ts25-36
• Transformers: Can use either postcss (default) or lightningcss (experimental) packages/vite/src/node/plugins/css.ts123-124
• URL Rewriting: Resolves url() and @import references in CSS, converting them to asset URLs or inlined data URLs.

Sources: packages/vite/src/node/plugins/css.ts:114-165(), packages/vite/src/node/plugins/css.ts:214-225()

assetPlugin

The assetPlugin manages static assets like images, fonts, and raw text files.

Key Functions:

• Inlining: Assets smaller than assetsInlineLimit are converted to Base64 data URLs packages/vite/src/node/plugins/asset.ts34-37
• Hashing: During build, assets are emitted with content-based hashes for cache busting packages/vite/src/node/plugins/asset.ts239-245
• ?raw Query: Supports loading file content as a string via import code from './file.txt?raw' packages/vite/src/node/plugins/asset.ts204-214

Sources: packages/vite/src/node/plugins/asset.ts:148-225()

htmlInlineProxyPlugin and buildHtmlPlugin

Vite treats index.html as a first-class entry point.

HTML Proxying: Inline <script> tags in HTML are extracted into virtual modules. For example, a script in index.html becomes a request to index.html?html-proxy&index=0.js packages/vite/src/node/plugins/html.ts59-61 This allows the standard transform pipeline (TS, JSX, etc.) to apply to inline code.

HTML Traversal: The traverseHtml function uses parse5 to walk the HTML AST and identify src, href, and srcset attributes that need resolution packages/vite/src/node/plugins/html.ts202-223

Sources: packages/vite/src/node/plugins/html.ts:103-137(), packages/vite/src/node/plugins/html.ts:202-223(), packages/vite/src/node/server/middlewares/indexHtml.ts:68-107()

importAnalysisPlugin and buildImportAnalysisPlugin

These plugins analyze and rewrite import statements.

Development Import Analysis:

• Rewrites bare imports to absolute paths packages/vite/src/node/plugins/importAnalysis.ts107-144
• Injects HMR boundaries and import.meta.hot API packages/vite/src/node/plugins/importAnalysis.ts225-230
• Tracks module dependencies in the ModuleGraph.

Build Import Analysis:

• Injects __vitePreload for preloading async chunks packages/vite/src/node/plugins/importAnalysisBuild.ts30-31
• The preload helper function manages the browser-side logic for preloading dependencies via <link rel="modulepreload"> packages/vite/src/node/plugins/importAnalysisBuild.ts62-163

Sources: packages/vite/src/node/plugins/importAnalysis.ts:196-223(), packages/vite/src/node/plugins/importAnalysisBuild.ts:5-163()

webWorkerPlugin

Handles the new Worker(new URL('./worker.js', import.meta.url)) pattern.

Worker Bundling: The bundleWorkerEntry function creates a separate Rolldown build for the worker entry point packages/vite/src/node/plugins/worker.ts162-211 This ensures workers have their own dependency graph and can be emitted as separate chunks or inlined.

Sources: packages/vite/src/node/plugins/worker.ts:162-211()

Core Plugin Execution Flow

The following diagram bridges the natural language description of a module request to the specific code entities involved.

Sources: packages/vite/src/node/plugins/oxc.ts:120-199(), packages/vite/src/node/plugins/importAnalysis.ts:225-360()

Plugin Data Flow and State

Many core plugins share state or use specific caches to optimize performance.

Cache Entity	Role	Source
htmlProxyMap	Stores code for inline HTML scripts	packages/vite/src/node/plugins/html.ts87-96
assetCache	Caches resolved asset URLs	packages/vite/src/node/plugins/asset.ts54
WorkerOutputCache	Prevents redundant worker bundling	packages/vite/src/node/plugins/worker.ts46-150
patternsCache	Caches regex patterns for define replacements	packages/vite/src/node/plugins/define.ts103-106

Sources: packages/vite/src/node/plugins/html.ts:87-152(), packages/vite/src/node/plugins/worker.ts:46-150(), packages/vite/src/node/plugins/css.ts:214-225()