https://github.com/gunar/ts-with

Enforce the presence of otherwise optional fields in TypeScript.
https://github.com/gunar/ts-with

Last synced: 6 days ago
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Enforce the presence of otherwise optional fields in TypeScript.

• Host: GitHub
• URL: https://github.com/gunar/ts-with
• Owner: gunar
• License: mit
• Created: 2019-03-12T17:58:40.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2019-03-12T18:25:59.000Z (over 5 years ago)
• Last Synced: 2024-09-22T04:18:06.735Z (about 2 months ago)
• Size: 2.93 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Installation

```

npm install --save @gunar/ts-with

```

# Summary

This package contains type maps for enforcing the presence of otherwise optional fields.

See the [blog post](https://medium.com/@gunar/narrower-optional-fields-for-typescript-49fd68335601) for more context.

## Example

```ts

interface User {

  name: string

  location?: string

}

// This passes type check but shouldn't ---------------------

const getTrimmedLocation = (u: User) => {

  if (u.location) return u.location.trim()

  else throw Error('User doesnt have a `location` field')

}

getTrimmedLocation({ name: 'Gunar' }) 

// This DOESN'T pass type check, as expected! ---------------

import { With } from '@gunar/ts-with'

const getTrimmedLocationSafe: (u: With) =>

  u.location.trim()

getTrimmedLocationSafe({ user: 'Gunar' })

```