Isomor Core

3.0.0 verified Fri May 01 auth: no javascript

Core library for isomor, a tool that abstracts frontend-backend communication in web applications by allowing direct server function calls from UI code without REST or GraphQL. Version 3.0.0 is current; the project uses a rolling release cadence. Key differentiators include automatic layer generation via Babel transpilation, tight code coupling, and TypeScript consistency. Isomor eliminates boilerplate and reduces overhead by keeping all code in a single project. The core package provides essential utilities and types.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module ↓

cause Using CommonJS require() with an ESM-only package.

fix

Switch to ES modules: use import statements or rename .js to .mjs.

error TypeError: isomor is not a function ↓

cause Using default import instead of named import, or using wrong import syntax.

fix

Use import { isomor } from 'isomor-core'.

error The requested module 'isomor-core' does not provide an export named 'default' ↓

cause Trying to import default export when only named exports exist.

fix

Use import { isomor } from 'isomor-core' instead of import isomor from 'isomor-core'.

Warnings

breaking v3.0.0 removes support for Node.js versions < 11. Ensure your environment uses Node.js >= 11. ↓

fix Upgrade to Node.js >= 11.

gotcha All exports are ESM-only; using require() will throw an error. ↓

fix Use import statements instead of require().

deprecated The `isomor` default export is deprecated; use named import instead. ↓

fix Replace `import isomor from 'isomor-core'` with `import { isomor } from 'isomor-core'`.

gotcha TypeScript type imports must use `import type` to avoid runtime side effects. ↓

fix Use `import type { ... } from 'isomor-core'` for type-only imports.

gotcha The `handler` export expects an object with async functions; passing synchronous functions may cause unexpected behavior. ↓

fix Ensure all handler methods return a Promise or use async/await.

Install

npm install isomor-core

yarn add isomor-core

pnpm add isomor-core

Imports

isomor

wrong

const isomor = require('isomor-core')

correct

import { isomor } from 'isomor-core'

ESM-only; CommonJS require is not supported.

IsomorOptions

wrong

import { IsomorOptions } from 'isomor-core'

correct

import type { IsomorOptions } from 'isomor-core'

Type-only import for TypeScript users; avoid runtime errors.

handler
```
import { handler } from 'isomor-core'
```
Named export; no default export available.

setupIsomor

wrong

const { setupIsomor } = require('isomor-core')

correct

import { setupIsomor } from 'isomor-core'

ESM-only; CJS require will fail.

Quickstart

Demonstrates calling a server function directly using isomor and defining a handler on the server side.

import { isomor, handler } from 'isomor-core';

const apiKey = process.env.API_KEY ?? 'default-key';

async function main() {
  const result = await isomor({
    url: '/api/greet',
    method: 'POST',
    headers: { 'X-API-Key': apiKey },
    body: { name: 'World' },
  });
  console.log('Result:', result);
}

handler({
  greet: async (name: string) => `Hello, ${name}!`,
});

main();