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    @typescript-runtime-schema/is
    TypeScript icon, indicating that this package has built-in type declarations

    0.3.0 • Public • Published

    @typescript-runtime-schema/is version

    is function to type guard against given type. To be used in conjunction with @typescript-runtime-schema/transform

    Installation

    Using npm:

    npm install @typescript-runtime-schema/is
    

    Using yarn:

    yarn add @typescript-runtime-schema/is
    

    Notes

    For this library to work the intended way you also need to add the transform function as a dependency and use it.

    npm install @typescript-runtime-schema/transform -D

    For how to use & setup the typescript transformer, please see Usage section of @typescript-runtime-schema/transform

    Usage

    Use the default exported is function to validate that a certain value conforms to a certain type.

    The is functions accepts a generic type as a type parameter and will type guard the value provided

    Examples

    // Basic example
    import is from '@typescript-runtime-schema/library'
    
    if(is<string>("Any human can tell this is a string, but a mere compiler won't know because it is cast" as any)) {
      console.log('Safe string zone')
    } else {
      console.log('Report issues at https://github.com/simonlovesyou/typescript-runtime-schema/issues')
    }

    It supports all type primitives (except unknown & never, because it wouldn't really make sense):

    • boolean
    • number
    • string
    • array
    • tuple
    • any
    • void
    • null
    • undefined
    • object

    The library supports heritage, intersections & unions

    import is from '@typescript-runtime-schema/library'
    
    type Animal = { type: 'vertebrates' | 'invertebrates' } & { cute: boolean }
    
    interface Human extends Animal {
      name: string
      age: number
      handedness: 'left' | 'right' | 'ambidextrous'
    }
    
    type Alien = { numberOfTentacles: number }
    
    const person = {
      name: 'Simon',
      age: 28,
      handedness: 'right',
      // cute: true /* Cuteness is in the eye of the beholder */ 
    }
    
    if(is<Alien | Human>(person as any)) {
      console.log("Alien or Human")
    } else {
      console.log("Not a Human or Alien")
    }

    API

    is

    Default export.

    Signature

    function is<T extends Serializable>(value: any) => value is T;

    Type Parameters

    Name Constraint Default value Description
    T Serializeable N/A The type we are type guarding against. Must be a serializeable value
    Serializeable

    type Serializeable = string | number | boolean | null | Record<string, Serializeable> | Serializeable[];

    Parameters

    Name Constraint Default value Description
    value N/A N/A The value we are type guarding

    Returns

    boolean: value is T

    License

    MIT License Copyright (c) 2021 Simon Johansson

    Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice (including the next paragraph) shall be included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Keywords

    none

    Install

    npm i @typescript-runtime-schema/is

    DownloadsWeekly Downloads

    13

    Version

    0.3.0

    License

    MIT

    Unpacked Size

    71.4 kB

    Total Files

    16

    Last publish

    Collaborators

    • simonlovesyou