namespace Hasher

Interface used to hash objects for hashed collections.

Companion interface: Hasher<UK>

Functions

anyDeepHasher

Returns a Hasher instance that hashes any value, and traverses into an object or array to hash its elements.

Definition

function anyDeepHasher(): Hasher<any>;

example

const h = Hasher.anyDeepHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => true
console.log(h.hash([{ a: 1, b: 2 }]) === h.hash([{ b: 2, a: 1 }]))
// => true

anyFlatHasher

Returns a Hasher instance that hashes any value, but never traverses into an object or array to hash its elements. In those cases it will use toString.

Definition

function anyFlatHasher(): Hasher<any>;

example

const h = Hasher.anyFlatHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => false

anyJsonStringHasher

Returns a Hasher instance that hashes any value by hashing the string resulting from applying JSON.stringify to the value.

Definition

function anyJsonStringHasher(): Hasher<any>;

example

const h = Hasher.anyJsonStringHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => false

anyShallowHasher

Returns a Hasher instance that hashes any value, but only traverses into an object or array to hash its elements one level deep. After one level, it will use toString.

Definition

function anyShallowHasher(): Hasher<any>;

example

const h = Hasher.anyShallowHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => true
console.log(h.hash([{ a: 1, b: 2 }]) === h.hash([{ b: 2, a: 1 }]))
// => false

anyToStringHasher

Returns a Hasher instance that hashes the string representation of any value.

Definition

function anyToStringHasher(maxStepBits?: number): Hasher<any>;

Parameters

Name	Type	Description
maxStepBits	number	the maximum amount of samples to take from the string

example

const h = Hasher.anyToStringHasher()
h.hash([1, 3, 'a'])

arrayHasher

Returns a Hasher that hashes arrays of elements by sampling the array and using the given itemHasher to hash the sampled elements.

Definition

function arrayHasher<T = any>(options?: {
    itemHasher?: Hasher<T>;
    maxStepBits?: number;
  }): Hasher<readonly T[]>;

Type parameters

Name	Description
T	the array element type

Parameters

Name	Type	Description
options	{     itemHasher?: Hasher<T>;     maxStepBits?: number;   }	(optional) an object containing the following items: - itemHasher: (optional) a Hasher instance used to hash elements in the array - maxStepBits: (optional) the amount of bits to determine the maximum amount of array elements to process

example

const h = Hasher.arrayHasher()
console.log(h.hash([1, 2, 3] === h.hash([1, 3, 2])))
// => false

bigintHasher

Returns a Hasher instance that hashes bigints.

Definition

function bigintHasher(): Hasher<bigint>;

example

const h = Hasher.bigintHasher()
console.log(h.hash(BigInt(5)) === h.hash(BigInt(10)))
// => false

booleanHasher

Returns a Hasher instance that hashes booleans.

Definition

function booleanHasher(): Hasher<boolean>;

example

const h = Hasher.booleanHasher()
console.log(h.hash(true) === h.hash(false))
// => false

createValueOfHasher

Returns a Hasher instance that hashes the .valueOf value of the given object using the given valueHasher for instances of the given cls class.

Definition

function createValueOfHasher<T extends {
    valueOf(): V;
  }, V>(cls: {
    new (): T;
  }, valueHasher?: Hasher<V>): Hasher<T>;

Type parameters

Name	Description
T	the input object type
V	the .valueOf property type

Parameters

Name	Type	Description
cls	{     new (): T;   }	the class containing the constructor to check for validity of a given object
valueHasher	Hasher<V>	the Hasher instance to use for the .valueOf values

example

const h = Hasher.createValueOfHasher(Date)
console.log(h.isValid(new Boolean(true)))
// => false
const d1 = new Date()
const d2 = new Date(d1)
console.log(h.hash(d1) === h.hash(d2))
// => true

dateHasher

Returns a Hasher instance that hashes Date values.

Definition

function dateHasher(): Hasher<Date>;

example

const h = Hasher.dateHasher()
const d1 = new Date()
const d2 = new Date(d1)
console.log(h.hash(d1) === h.hash(d2))
// => true

defaultHasher

Returns the default Hasher instance used by hashed collections.

Definition

function defaultHasher(): Hasher<any>;

example

const h = Hasher.defaultHasher()
h.hash({ a: 1, b: 2 })

numberHasher

Returns a Hasher instance that hashes numbers, including 'special' values like NaN and infinities.

Definition

function numberHasher(): Hasher<number>;

example

const h = Hasher.numberHasher()
console.log(h.hash(Number.POSITIVE_INFINITY) === h.hash(Number.NEGATIVE_INFINITY))
// => false
console.log(h.hash(Number.NaN) === h.hash(Number.NaN))
// => true

objectDeepHasher

Returns a Hasher instance that hashes objects of key type K and value type V. If a value is an object or array, it will recursively hash its values.

Definition

function objectDeepHasher<K extends string |number|symbol, V = any>():Hasher<Record<K, V>>;

Type parameters

Name	Description
K	the key type
V	the value type

note

be careful with circular structures, they can cause an infinite loop

example

const h = Hasher.objectDeepHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => true

objectHasher

Returns a Hasher instance that hashes objects of key type K and value type V.

Definition

function objectHasher<K extends string |number| symbol, V = any>(options?: {
    keyHasher: Hasher<K>;
    valueHasher: Hasher<V>;
  }): Hasher<Record<K, V>>;

Type parameters

Name	Description
K	the key type
V	the value type

Parameters

Name	Type	Description
options	{     keyHasher: Hasher<K>;     valueHasher: Hasher<V>;   }	(optional) an object containing: - keyHasher: (optional) a Hasher instance that is used to hash object keys - valueHasher: (optional) a Hasher instance that is used to hash object values

example

const h = Hasher.objectHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => true

objectShallowHasher

Returns a Hasher instance that hashes objects of key type K and value type V. If a value is an object or array, it will convert those values to a string.

Definition

function objectShallowHasher<K extends string |number|symbol, V = any>():Hasher<Record<K, V>>;

Type parameters

Name	Description
K	the key type
V	the value type

example

const h = Hasher.objectShallowHasher()
console.log(h.hash({ a: 1, b: 2 }) === h.hash({ b: 2, a: 1 }))
// => true

streamSourceHasher

Returns a Hasher instance that hashes any StreamSource limited to a certain amount of elements to prevent hanging on infinite streams.

Definition

function streamSourceHasher<T = any>(options?: {
    itemHasher?: Hasher<T>;
    maxStepBits?: number;
  }): Hasher<StreamSource<T>>;

Type parameters

Name	Description
T	the StreamSource element type

Parameters

Name	Type	Description
options	{     itemHasher?: Hasher<T>;     maxStepBits?: number;   }	(optional) an object containing the following items: - itemHasher: (optional) a Hasher instance used to hash elements in the array - maxStepBits: (optional) the amount of bits to determine the maximum amount of array elements to process

example

const h = Hasher.streamSourceHasher()
h.hash(Stream.random())
// infinite stream but will not hang due to the max step limit

stringCaseInsensitiveHasher

Returns a Hasher instance for case-insensitive string values.

Definition

function stringCaseInsensitiveHasher(): Hasher<string>;

example

const h = Hasher.stringCaseInsensitiveHasher()
console.log(h.hash('Abc') === h.hash('aBC'))
// => true

stringHasher

Returns a Hasher instance for string values.

Definition

function stringHasher(): Hasher<string>;

example

const h = Hasher.stringHasher()
h.hash('abc')

tupleSymmetric

Returns a Hasher that will return equal hash values for values in a tuple regardless of their order, and uses the given hasher function to hash the tuple elements.

Definition

function tupleSymmetric<T>(hasher?: Hasher<T>): Hasher<readonly [T, T]>;

Type parameters

Name	Description
T

Parameters

Name	Type	Description
hasher	Hasher<T>	the Hasher instance to use for tuple elements

example

const h = Hasher.tupleSymmetric()
console.log(h.hash(['abc', 'def']) === h.hash(['def', 'abc']))