moy-fp/src/Relation/equals.js

A functional programming library.

import curry from '../Function/curry'

/**
 * a -> a -> Boolean
 */
const equals = curry(
  (b, a) => {
    if(Object.is(a, b)){
      return true
    }
    const aType = Object.prototype.toString.call(a),
          bType = Object.prototype.toString.call(b)
    if(aType !== bType){
      return false
    }
    if(aType === '[object Array]'){
      if(a.length !== b.length){
        return false
      }
      const length = a.length;
      for(let i = 0; i < length; i++){
        if(!equals(b[i], a[i])){
          return false
        }
      }
      return true
    }
    if(aType === '[object Object]'){
      const aEntries = Object.entries(a),
            bEntries = Object.entries(b)
      if(aEntries.length !== bEntries.length){
        return false
      }
      return equals(bEntries, aEntries)
    }
    if(aType === '[object Function]'){
      return a.toString() === b.toString()
    }
    if(aType === '[object Date]'){
      return a.valueOf() === b.valueOf()
    }
    if(aType === '[object RegExp]'){
      return a.source === b.source &&
          a.global === b.global &&
          a.ignoreCase === b.ignoreCase &&
          a.multiline === b.multiline &&
          a.sticky === b.sticky &&
          a.unicode === b.unicode &&
          a.dotAll === b.dotAll
    }
    return false
  }
)

export default equals