simred/src/deep/merge.js

A simple redux-like application state manager

// From https://github.com/KyleAMathews/deepmerge
import defaultIsMergeableObject from './ismergeable'

function emptyTarget(val) {
  return Array.isArray(val) ? [] : {}
}

function cloneUnlessOtherwiseSpecified(value, options) {
  return (options.clone !== false && options.isMergeableObject(value)) ?
    deepmerge(emptyTarget(value), value, options) :
    value
}

// function defaultArrayMerge(target, source, options) {
//   return target.concat(source).map(function (element) {
//     return cloneUnlessOtherwiseSpecified(element, options)
//   })
// }

function mergeObject(target, source, options) {
  var destination = {}

  /* istanbul ignore else */
  if (options.isMergeableObject(target)) {
    Object.keys(target).forEach(function (key) {
      destination[key] = cloneUnlessOtherwiseSpecified(target[key], options)
    })
  }
  Object.keys(source).forEach(function (key) {
    if (!options.isMergeableObject(source[key]) || !target[key]) {
      destination[key] = cloneUnlessOtherwiseSpecified(source[key], options)
    } else {
      destination[key] = deepmerge(target[key], source[key], options)
    }
  })
  return destination
}

export function deepmerge(target, source, options) {
  if ("string" == typeof source) return source
  if ("object" != typeof target && "object" != typeof source) return source
  // if ("string" == typeof target && "string" == typeof source) return source
  // if ("number" == typeof target && "number" == typeof source) return source
  options = options  //|| {}
  options.arrayMerge = options.arrayMerge // || defaultArrayMerge
  options.isMergeableObject = /* options.isMergeableObject ||*/ defaultIsMergeableObject

  var sourceIsArray = Array.isArray(source)
  var targetIsArray = Array.isArray(target)
  var sourceAndTargetTypesMatch = sourceIsArray === targetIsArray

  if (!sourceAndTargetTypesMatch) {
    return cloneUnlessOtherwiseSpecified(source, options)
  } else if (sourceIsArray) {
    return options.arrayMerge(target, source, options)
  } else {
    return mergeObject(target, source, options)
  }
}

// deepmerge.all = function deepmergeAll(array, options) {
//   if (!Array.isArray(array)) {
//     throw new Error('first argument should be an array')
//   }

//   return array.reduce(function (prev, next) {
//     return deepmerge(prev, next, options)
//   }, {})
// }