ts-validator

Asserts values at runtime and compile time for type validity.

Installation

Local installation using git submodules.

mkdir git_modules
git submodule add https://github.com/onbo-moth/ts-validator/ git_modules/ts-validator
npm install ./git_modules/ts-validator 

Using in package.json

Add following line to dependencies section:

{
  "dependencies": {
    // ...
    "ts-validator": "github:onbo-moth/ts-validator",
    // ...
  }
}

Basic Usage

import { Validator } from "ts-validator"

/// "abc" strongly typed as string.
const value = new Validator( "abc" as unknown ).assertToString().getValue()  

// throws TypeValidationError, because 123 is not a string.
const error = new Validator( 123 as unknown ).assertToString().getValue()

Features

Basic Type Checks

new Validator( 42   ).assertToNumber()
new Validator( true ).assertToBoolean()
new Validator( null ).assertToNull()

Boolean Methods

These methods check without throwing an error.

const value = new Validator( 99 )

console.log( value.isNumber() ) // true
console.log( value.isString() ) // false

Access methods ( containsProperty(), assertAndSelectProperty() )

Retrieves properties safely.

const obj = new Validator( { id: 12, name: "Marco" } )

console.log( obj.containsProperty( "id"  ) ) // true
console.log( obj.containsProperty( "age" ) ) // false

console.log( obj.assertAndSelectProperty( "id" ).getValue() ) // 12

Static assertion methods

Standalone functions for validating values.

Validator.assertToNumber( 42   ) // Doesn't throw. 
Validator.assertToNumber( "42" ) // Throws an error. 

Static nullable assertion methods

// Both work!
Validator.assertToNumberOrNull( 42 )
Validator.assertToNumberOrNull( null )

// This doesn't work!
Validator.assertToNumberOrNull( 42 )

Array checks ( assertArrayOf() )

Ensures all elements in an array follow a type.

const numbers = new Validator( [ 1, 2, 3 ] as unknown )

numbers.assertArrayOf( Validator.assertToNumber ).getValue() // [ 1, 2, 3 ] typed as number[]
numbers.assertArrayOf( Validator.assertToString ).getValue() // Throws an error, because it fails string assertion.

Object checks ( assertContains() )

Checks if an object contains specific keys with given types.

const obj = new Validator( { id: 13, name: "Alice" } as unknown )

obj.assertContains( {
  id:   Validator.number,
  name: Validator.string
} )

obj.getValue() // type contains { id: number, name: string }