deepCompare

deepCompare.ts

const { toString } = Object.prototype

/** Any object type */
type AnyObj = { [key: string]: any }

export function deepCompare(a: any, b: any): boolean {
  // Strict equality
  if (a === b) return true

  // Some types get special treatment
  if (a && a.constructor == b.constructor && typeof a == 'object') {
    switch (toString.call(a).slice(8, -1)) {
      case 'Array':
        return arrayCompare(a, b)
      case 'Object':
        return objectCompare(a, b)
      case 'Date':
        return +a === +b
      case 'RegExp':
        return a.toString() == b.toString()
    }
  }

  // NaN equality
  return a !== a && b !== b
}

function arrayCompare(a: any[], b: any[]): boolean {
  let len = a.length
  if (len != b.length) return false
  for (let i = 0; i < len; i++) {
    if (!deepCompare(a[i], b[i])) return false
  }
  return true
}

function objectCompare(a: AnyObj, b: AnyObj): boolean {
  let ak = Object.keys(a)
  let bk = Object.keys(b)
  let len = ak.length
  if (len != bk.length) return false
  for (let i = 0; i < len; i++) {
    let key = ak[i]
    if (bk.indexOf(key) == -1) return false
  }
  for (let i = 0; i < len; i++) {
    let key = bk[i]
    if (ak.indexOf(key) == -1 || !deepCompare(a[key], b[key])) return false
  }
  return true
}