typings-esm-loader

ESM Loader Typings

Typings for Node.js custom ESM loaders

Node.js custom ESM loaders need to be written in JS as they're passed directly to Node.js on startup, but that doesn't mean we can't have types on them.

Install

npm i -D jhmaster2000/typings-esm-loader

Usage

At the top of your loader's JS file:

/// <reference types="typings-esm-loader" />
/// @ts-check

The /// @ts-check line is optional and can be removed if you only want type hints with no strict type checking.

You can now use JSDoc comments to typecast your hooks to their respective types as such:

/** @type {resolve} */
export async function resolve(specifier, context, defaultResolve) { ... }

/** @type {load} */
export async function load(url, context, defaultLoad) { ... }

/** @type {globalPreload} */
export function globalPreload() { ... }

Other types provided

• Loader: an interface representing an ESM loader when imported as a module, useful when multiloading.
• TypedArray: a union type representing all built-in TypedArray objects. Used for load hook's return value source field.
• ModuleFormat: a union type representing all valid module formats to pass to the load hook's return value format field.
• getBuiltin: a type declaration for the function of same name provided in the global scope of globalPreload hook's scripts.
• namespace Resolve
  • Context: the interface representing the import context object passed to resolve hooks.
  • Return: the interface representing the required return type of resolve hooks.
  • Function: structurally identical to resolve type, used to disambiguate between the user's hook (resolve) and the resolve function argument passed to it.
• namespace Load
  • Context: the interface representing the import context object passed to load hooks.
  • Return: the interface representing the required return type of load hooks.
  • Function: structurally identical to load type, used to disambiguate between the user's hook (load) and the load function argument passed to it.