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jsconfig.json option

moduleResolution

  • Default node10
  • Tested with TypeScript 5.9

moduleResolution is the lookup algorithm: given "./format" or "some-package/sub", which file does the import mean? nodenext applies Node's rules (extensions required in ES modules, exports maps honored); bundler applies the looser rules bundlers share (extensions optional, exports read with the import condition).

module: "nodenext" implies nodenext and module: "preserve" implies bundler, so most configs never write it. bundler arrived with TypeScript 5.0. The old node10 (also spelled node) ignores exports maps and is deprecated from TypeScript 6.0; classic is removed there.

At a glance

Write Usually nothing: let module imply it. Write "bundler" next to module: "esnext"
On the command line --moduleResolution
Type string
Default in TypeScript 5.9 node10 (with module: "commonjs"; module nodenext implies nodenext, and preserve implies bundler)
TypeScript's description Specify how TypeScript looks up a file from a given module specifier.
In the quick-start setups

The description is quoted from TypeScript's own option list (Apache-2.0); see the notices. The setup values are the checked configs on the quick-start pages.

Examples

main.js Error confirmed 5.9.3 TypeScript 5.9.3, run 21 October 2026: main.js(2,29): error TS2835: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Did you mean './format.js'? 6.0.3 TypeScript 6.0.3, run 21 October 2026: the same as 5.9.3. main.js(2,29): error TS2835: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Did you mean './format.js'? 7.0.2 TypeScript 7.0.2, run 21 October 2026: the same as 5.9.3. main.js(2,29): error TS2835: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Did you mean './format.js'? checked 21 October 2026 
import { formatPrice } from "./format";error TS2835: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Did you mean './format.js'?

console.log(formatPrice(1999));
moduleResolution nodenext: a relative import needs its extension.
jsconfig.json for this example 
{
  "compilerOptions": {
    "checkJs": true,
    "noEmit": true,
    "strict": true,
    "target": "es2022",
    "module": "nodenext",
    "types": []
  },
  "include": [
    "*.js"
  ]
}
main.js TypeScript 5.9.3 TypeScript 5.9.3, run 21 October 2026: No errors. 6.0.3 TypeScript 6.0.3, run 21 October 2026: the same as 5.9.3. No errors. 7.0.2 TypeScript 7.0.2, run 21 October 2026: the same as 5.9.3. No errors. checked 21 October 2026 
import { formatPrice } from "./format";

console.log(formatPrice(1999));
moduleResolution bundler: an import without its extension passes, because a bundler fills it in.
jsconfig.json for this example 
{
  "compilerOptions": {
    "checkJs": true,
    "noEmit": true,
    "strict": true,
    "target": "es2022",
    "module": "preserve",
    "types": [],
    "moduleResolution": "bundler"
  },
  "include": [
    "*.js"
  ]
}

Which one matches your project

Choose by who resolves the imports when the code runs. If Node.js loads your files directly, use nodenext, so the checker refuses imports that Node.js would refuse. If a bundler, Bun, or a framework's build resolves them, use bundler, so the checker accepts what that tool accepts. A browser that loads <script type="module"> files without a bundler needs exact relative URLs, which nodenext with "type": "module" enforces; TypeScript's handbook suggests that pairing for unbundled browser code.

Gotchas

  • With bundler, the checker accepts import "./format", but Node.js would not. Use it only for code that something other than Node.js resolves.
  • An import the checker cannot resolve is an error only when it binds something; import "./polyfill.js" with a wrong path passes unless noUncheckedSideEffectImports is on.

  • jsconfig.json option

    module

    module tells the checker which module system your .js files follow: Node's rules with nodenext, a bundler's with preserve. Set it, even with noEmit.

  • jsconfig.json option

    paths and baseUrl

    paths maps import names to files for the checker, such as @lib/* to src/lib/*. It does not change how Node.js resolves imports; package.json imports does.

  • jsconfig.json option

    customConditions

    customConditions adds export conditions, like development, that TypeScript uses when it reads a package's exports map. Match what your runtime or bundler uses.

  • TypeScript error

    TS2307: An import the checker cannot resolve

    TS2307 means an import path resolves to nothing the checker can read: a package not installed, a typo, or a CSS or image file. Install it or declare the module.

  • TypeScript error

    TS2792: Packages not found because module resolution is classic

    TS2792 means module set to an ES year without moduleResolution left TypeScript 5.9 on its old classic lookup, which misses most packages. Set moduleResolution.

  • TypeScript error

    TS2835: A relative import without its file extension

    TS2835 and TS2834 mean an ES module imports ./file or ./folder without .js under nodenext, which Node.js does not resolve. Write the full path, or use bundler.

Sources

Last reviewed 20 October 2026.