1---
2title: Prefer Statically Analyzable Paths
3impact: HIGH
4impactDescription: avoids accidental broad bundles and file traces
5tags: bundle, nextjs, vite, webpack, rollup, esbuild, path
6---
7 
8## Prefer Statically Analyzable Paths
9 
10Build tools work best when import and file-system paths are obvious at build time. If you hide the real path inside a variable or compose it too dynamically, the tool either has to include a broad set of possible files, warn that it cannot analyze the import, or widen file tracing to stay safe.
11 
12Prefer explicit maps or literal paths so the set of reachable files stays narrow and predictable. This is the same rule whether you are choosing modules with `import()` or reading files in server/build code.
13 
14When analysis becomes too broad, the cost is real:
15- Larger server bundles
16- Slower builds
17- Worse cold starts
18- More memory use
19 
20### Import Paths
21 
22**Incorrect (the bundler cannot tell what may be imported):**
23 
24```ts
25const PAGE_MODULES = {
26  home: './pages/home',
27  settings: './pages/settings',
28} as const
29 
30const Page = await import(PAGE_MODULES[pageName])
31```
32 
33**Correct (use an explicit map of allowed modules):**
34 
35```ts
36const PAGE_MODULES = {
37  home: () => import('./pages/home'),
38  settings: () => import('./pages/settings'),
39} as const
40 
41const Page = await PAGE_MODULES[pageName]()
42```
43 
44### File-System Paths
45 
46**Incorrect (a 2-value enum still hides the final path from static analysis):**
47 
48```ts
49const baseDir = path.join(process.cwd(), 'content/' + contentKind)
50```
51 
52**Correct (make each final path literal at the callsite):**
53 
54```ts
55const baseDir =
56  kind === ContentKind.Blog
57    ? path.join(process.cwd(), 'content/blog')
58    : path.join(process.cwd(), 'content/docs')
59```
60 
61In Next.js server code, this matters for output file tracing too. `path.join(process.cwd(), someVar)` can widen the traced file set because Next.js statically analyze `import`, `require`, and `fs` usage.
62 
63Reference: [Next.js output](https://nextjs.org/docs/app/api-reference/config/next-config-js/output), [Next.js dynamic imports](https://nextjs.org/learn/seo/dynamic-imports), [Vite features](https://vite.dev/guide/features.html), [esbuild API](https://esbuild.github.io/api/), [Rollup dynamic import vars](https://www.npmjs.com/package/@rollup/plugin-dynamic-import-vars), [Webpack dependency management](https://webpack.js.org/guides/dependency-management/)
64