hashCodeObject

This package is used to set hashCode property to a object.

Install

npm install --save hashcodeobject

Usage

import { defineDeepHashCodeObject } from 'hashcodeobject'

var obj = { a: { b: 10 } }
defineDeepHashCodeObject(obj)

console.log(obj.hashCode)
console.log(obj.a.hashCode)

API

getObjectHashCode(obj)

Get hash code from a given object/array.

import { getObjectHashCode } from 'hashcodeobject'
let hashCode = getObjectHashCode({ a: [ 1, 3, 4 ] })

defineObjectHashCodeProperty(obj)

Use defineProperty to set a new property to the given object/array, so that you can use obj.hashCode to get hash code.

Hash code is cached on obj._hashCodeCache, the first time you call obj.hashCode, caculation will be run, but the second time, cache will be used.

If you change a property of this object, cache will be clear, caculation will be run again the next time you call obj.hashCode.

createHashCodeObject(obj)

defineObjectHashCodeProperty listen to the top level properties, however, some objects have children in which there are objects too. For example:

var obj = {
  x: 1,
  children: {
    y: 2,
  },
}

This is not fit to use defineObjectHashCodeProperty, it is better to use createHashCodeObject.

import { createHashCodeObject } from 'hashcodeobject'
createHashCodeObject(obj)
obj.children.y = 3 // obj.hashCode changed

getComplexObjectHashCode(obj)

All of above methods do not support objects that has circle structure, i.e.

let a = { x: 1 }
let b = { y: 1, a }
a.b = b

Here a.b === b, and b.a === a, it is not possible to use JSON.stringify.

To resolve this problem, you'd better to use getComplexObjectHashCode to get hash code here:

import { getComplexObjectHashCode } from 'hashcodeobject'
let hash = getComplexObjectHashCode(a)
console.log(hash)

However, it is not recommend to use circle structed object to caculate hash code. So I do not provide defineComplexHashCodeObject.