isoftype-ts

Helps you to safely assign a type to an object. Can be used when receiving an union or when fetching from a remote data source. When taking a type argument, let's you only pick keys from the specified type and if the check passes assigns the type. If used without a type argument the object will be of type Record<string | number | symbol, unknown> afterwards. Can either only be used with a key, or with a key and value. First checks for presence of the key in the object, second keys into the object and compares against the provided value.

Install

Install using npm:

$ npm install --save isoftype-ts

Usage

import isOfType from "isoftype-ts"

Use as so:

type Person = {
  name: string
  height: string
}

type Starship = {
  name: string
  crew: number
}

const foo = (bar: Person | Starship) => {
    if(isOfType<Person>(bar, 'height')) {
        // bar has the type Person now and all properties can safely be accessed!
        return "It's a person!"
    } else {
        // bar has the type Starship now and all properties can safely be accessed!
        return "It's a starship!"
    }
}

Author

Tom Heinemeyer

• GitHub Profile

License

Copyright © 2024, Tom Heinemeyer. Released under the MIT License.