bootstrap-vue/src/utils/loose-equal.js

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import { hasOwnProperty, keys } from './object'
import { isArray, isDate, isObject } from './inspect'

// Assumes both a and b are arrays!
// Handles when arrays are "sparse" (array.every(...) doesn't handle sparse)
const compareArrays = (a, b) => {
  if (a.length !== b.length) {
    return false
  }
  let equal = true
  for (let i = 0; equal && i < a.length; i++) {
    equal = looseEqual(a[i], b[i])
  }
  return equal
}

/**
 * Check if two values are loosely equal - that is,
 * if they are plain objects, do they have the same shape?
 * Returns boolean true or false
 */
export const looseEqual = (a, b) => {
  if (a === b) {
    return true
  }
  let aValidType = isDate(a)
  let bValidType = isDate(b)
  if (aValidType || bValidType) {
    return aValidType && bValidType ? a.getTime() === b.getTime() : false
  }
  aValidType = isArray(a)
  bValidType = isArray(b)
  if (aValidType || bValidType) {
    return aValidType && bValidType ? compareArrays(a, b) : false
  }
  aValidType = isObject(a)
  bValidType = isObject(b)
  if (aValidType || bValidType) {
    /* istanbul ignore if: this if will probably never be called */
    if (!aValidType || !bValidType) {
      return false
    }
    const aKeysCount = keys(a).length
    const bKeysCount = keys(b).length
    if (aKeysCount !== bKeysCount) {
      return false
    }
    for (const key in a) {
      const aHasKey = hasOwnProperty(a, key)
      const bHasKey = hasOwnProperty(b, key)
      if ((aHasKey && !bHasKey) || (!aHasKey && bHasKey) || !looseEqual(a[key], b[key])) {
        return false
      }
    }
  }
  return String(a) === String(b)
}