# emery

> Utilities to help polish the rough parts of TypeScript.

Latest version **1.4.4** (published 2025-04-07) · MIT license · 0 weekly downloads

## Install

```sh
npm install emery
pnpm add emery
yarn add emery
bun add emery
```

## Health

**Score 55/100 (C)** — status: stable.

Positive: has types; esm support; no vulnerabilities; high maintenance score; high quality score.

Warnings: low downloads.

Negative: stale.

## Facts

| | |
|---|---|
| Version | 1.4.4 |
| Published | 2025-04-07 |
| First published | 2022-05-31 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 0 |
| Unpacked size | 85.1 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 85 |
| Author | jossmac |
| Maintainers | jossmac, emery-release-bot, emmatown |
| Keywords | ts, typescript, utils, utilities |

## Links

- npm: https://www.npmjs.com/package/emery
- Repository: https://github.com/thinkmill/emery
- Homepage: https://emery-ts.vercel.app
- Issues: https://github.com/thinkmill/emery/issues
- npm.io page: https://npm.io/package/emery

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## Recent versions

- 1.4.4 (latest) — 2025-04-07
- 1.4.3 — 2024-01-15
- 1.4.2 — 2023-03-22
- 1.4.1 — 2022-07-07
- 1.4.0 — 2022-07-07
- 1.3.0 — 2022-07-06
- 1.2.2 — 2022-06-30
- 1.2.1 — 2022-06-24
- 1.2.0 — 2022-06-24
- 1.1.0 — 2022-05-31
- 1.0.0 — 2022-05-31

## README

# Emery

<a href="https://emery-ts.vercel.app/">
  <img alt="Polish for the rough parts of TypeScript" src=".github/assets/banner.svg">
</a>
<p>
  <a title="View on npm" href="https://www.npmjs.com/package/emery">
    <img alt="npm version" src="https://img.shields.io/npm/v/emery.svg?style=for-the-badge&labelColor=0869B8">
  </a>
  <a title="View the project license" href="LICENSE">
    <img alt="License SDPX identifier" src="https://img.shields.io/npm/l/emery.svg?style=for-the-badge&labelColor=579805">
  </a>
  <a title="View emery website" href="https://emery-ts.vercel.app/">
    <img alt="Website" src="https://img.shields.io/badge/Website-2F6BFF.svg?style=for-the-badge&logo=data:image/svg+xml;base64,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&labelColor=0737ad&locoColor=white&logoWidth=0">
  </a>
  <a title="Visit Thinkmill" href="https://www.thinkmill.com.au/open-source?utm_campaign=github-emery">
    <img alt="A Thinkmill project" src="https://img.shields.io/badge/A%20Thinkmill%20Project-ed0000.svg?style=for-the-badge&logo=data:image/svg+xml;base64,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&labelColor=C60200&locoColor=white&logoWidth=0">
  </a>
</p>

---

💎 Polish for the rough parts of TypeScript.

TypeScript is great but there's parts that are still rough around the edges, especially for developers who are new to the language.

## Purpose and intent

Emery is a small collection of utilities that improve DX without compromising static types.

### Check for ambiguous types

Emery exposes "checks" for dealing with ambiguous types.

Checks are just predicates that can't be expressed as type guards, without enforcing opaque types.

```ts
import { checkAll, isNonNegative, isInteger } from 'emery';

/**
 * Along with some default check functions, we provide helpers
 * for managing combinations. The `checkAll` helper is a bit
 * like `pipe` for predicates.
 */
export const isNonNegativeInteger = checkAll(isNonNegative, isInteger);
```

### Assert the validity of props

An assertion declares that a condition be true before executing subsequent code, ensuring that whatever condition is checked must be true for the remainder of the containing scope.

```ts
import { assert } from 'emery';

import { isNonNegativeInteger } from './path-to/check';

function getThingByIndex(index: number) {
  assert(isNonNegativeInteger(index));

  return things[index]; // 🎉 Safely use the `index` argument!
}
```

### Smooth over loose types

Utility functions for smoothing over areas of TypeScript that are loosely typed.

Because of JavaScript's dynamic implementation the default TS behaviour is correct, but can be frustrating in certain situations.

```ts
import { typedKeys } from 'emery';

const obj = { foo: 1, bar: 2 };

const thing = Object.keys(obj).map(key => {
  return obj[key]; // 🚨 'string' can't be used to index...
});
const thing2 = typedKeys(obj).map(key => {
  return obj[key]; // 🎉 No more TypeScript issues!
});
```

## Philosophy and motivation

Like all good things, Emery started with curiosity. At [Thinkmill](https://thinkmill.com.au/) we have an internal Slack channel for TypeScript where a question was raised about how to offer consumers error messages that convey intent, not just cascading type failures.

While that's not currently possible, it became apparent that there was demand for a solution. We also discovered that many developers were carrying around miscellaneous utilities for working with TypeScript between projects.

---

## License

Copyright (c) 2023
[Thinkmill Labs](https://www.thinkmill.com.au/labs?utm_campaign=github-emery)
Pty Ltd. Licensed under the MIT License.

---
_Source: https://npm.io/package/emery · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._