substance/util/merge.js

Substance is a JavaScript library for web-based content editing. It provides building blocks for realizing custom text editors and web-based publishing system. It is developed to power our online editing platform [Substance](http://substance.io).

// TODO: rename this module to avoid confusion with lodash-es/merge
import { merge as _merge, mergeWith as _mergeWith } from '../vendor/lodash-es'
import isArray from './isArray'

/**
  Same as lodash/merge except that it provides options how to
  treat arrays.

  The default implementation overwrites elements.
   get concatenated rather than overwritten.
*/
export default function merge (a, b, options) {
  options = options || {}
  var _with = null
  if (options.array === 'replace') {
    _with = _replaceArrays
  } else if (options.array === 'concat') {
    _with = _concatArrays
  }
  if (_with) {
    return _mergeWith(a, b, _with)
  } else {
    return _merge(a, b)
  }
}

function _concatArrays (objValue, srcValue) {
  if (isArray(objValue)) {
    return objValue.concat(srcValue)
  } else {
    return null
  }
}

function _replaceArrays (objValue, srcValue) {
  if (isArray(objValue)) {
    return srcValue
  } else {
    return null
  }
}