Utility to dynamically load ESM modules in TypeScript CommonJS projects
npm install load-esm
load-esm is a tiny utility that lets CommonJS (CJS) TypeScript projects dynamically import pure ESM packages at runtime—without hacks like eval().
It helps avoid errors like:
* Error [ERR_REQUIRE_ESM]: require() of ES Module
* Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: No "exports" main defined in ...
---
``bash`
npm install load-esmor
yarn add load-esmor
pnpm add load-esm
> Works in CJS TypeScript projects. No config changes required.
---
`ts
// TypeScript (CJS project)
import { loadEsm } from "load-esm";
(async () => {
const esmModule = await loadEsm("esm-module");
// use esmModule...
})();
`
`ts
import { loadEsm } from "load-esm";
(async () => {
const esmModule = await loadEsm
// esmModule is fully typed
})();
`
`ts
import { loadEsm } from "load-esm";
(async () => {
try {
// Import a pure ESM package from a CommonJS TS project
const { fileTypeFromFile } = await loadEsm
"file-type"
);
const type = await fileTypeFromFile("fixture.gif");
console.log(type);
} catch (error) {
console.error("Error importing module:", error);
}
})();
`
> Note: Because top‑level await isn’t available in CommonJS, examples use an async IIFE.
---
`ts`
function loadEsm
Parameters
* name — Package name or file path to import.
Returns
* Promise resolving to the imported module namespace.
---
In CJS TypeScript projects ("module": "commonjs"), the TS compiler transpiles dynamic import() to require(), which breaks when the target is a pure ESM package.
load-esm executes the import() outside of TypeScript’s transpilation scope, preserving native dynamic import() semantics at runtime. This keeps your code type‑safe while avoiding brittle workarounds (e.g., wrapping import() in eval()).
Since Node.js 22.12, require can load some ESM modules, but there are documented constraints. If your dependencies are compatible with that path, you might not need this utility. load-esm remains useful when:
* You’re on older Node.js versions that support import() (see Compatibility) but not the newer require() behavior.
* You want a single, consistent pattern that works across environments and avoids edge cases.
> If Node’s built‑in require(esm) works for your packages and version, feel free to use it.
---
* Node.js: ≥ 13.2.0 (first version with native import() support)
* TypeScript: Fully typed; works in CJS projects.
---
* ERR_REQUIRE_ESM: Ensure you’re using load-esm(...) to import the ESM dependency from CJS code.No "exports" main defined
* : Some packages only expose ESM entry points. Import them via load-esm.loadEsm
* Type declarations: Use the generic form
* Top‑level await: Wrap usage in an async IIFE in CJS.
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See Releases.
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Inspired by common pain points when mixing CJS projects with modern ESM‑only libraries.