Sidewinder Value

Operations on dynamic JavaScript values

Overview

Sidewinder Value is a library that provides advanced operations on JavaScript values. It offers functionality ranging from creating values from Sidewinder types, upcasting values from types and diffing and patching values. All functions of this library are immutable.

License MIT

Contents

• Overview
• Install
• Usage
• Clone
• Create
• Check
• Diff
• Patch
• Upcast

Install

$ npm install @sidewinder/value

Clone

The clone function will deep clone a JavaScript value.

import { Value } from '@sidewinder/value'

const A = Value.Clone(1) // 1
const B = Value.Clone(true) // true
const C = Value.Clone('hello') // hello
const D = Value.Clone([1, 2, 3]) // [1, 2, 3]
const E = Value.Clone({ x: 1, y: 1 }) // { x: 1, y: 1}

Create

The create function will create a JavaScript value from a Sidewinder type. If the type provides a default value, this value will be used to create the associated value.

import { Value, Type } from '@sidewinder/type'

const T = Type.Object({
  x: Type.Number({ default: 0 }),
  y: Type.Number({ default: 0 }),
  z: Type.Number({ default: 0 }),
  w: Type.Number({ default: 1 }),
})

// const value = { x: 0, y: 0, z: 0, w: 1 }
const value = Value.Create(T)

Check

The check function performs a fast runtime type check on a given value. Note that this function checks based on the kind property of the type, and is not a JSON schema check.

import { Value, Type } from '@sidewinder/type'

const T = Type.Object({
  x: Type.Number({ default: 0 }),
  y: Type.Number({ default: 0 }),
  z: Type.Number({ default: 0 }),
  w: Type.Number({ default: 1 }),
})

// const check = true
const check = Value.Check({ x: 1, y: 1, z: 1, w: 2 })

Diff

The diff function will produce a series of operational edits to transform one value into another. This function is used with the patch function to apply patches to JavaScript values where.

import { Value } from '@sidewinder/type'

const A = { x: 1, y: 1 }
const B = { x: 2, y: 2, z: 2 }

const E = Value.Diff(A, B) // Edit[]

Patch

The diff function will produce a series of operational edits to transform one value into another. This function is used with the patch function to apply patches to JavaScript values where.

import { Value } from '@sidewinder/type'
const A = { x: 1, y: 1 }
const B = { x: 2, y: 2, z: 2 }
const E = Value.Diff(A, B)
const C = Value.Patch(A, E)

assert.deepEqual(B, C)

Upcast

The upcast function will attempt to cast an existing value to the target type while preserving as much information as possible.

import { Value, Type } from '@sidewinder/type'

const T = Type.Object({
  id: Type.String()
  x: Type.Number({ default: 0 }),
  y: Type.Number({ default: 0 }),
  z: Type.Number({ default: 0 }),
})

// const value = { id: '', x: 1, y: 1, z: 1 }
const value = Value.Upcast(T, { x: 1, y: 1, z: 1, w: 2 })