@coreui/coreui-pro/js/src/utilities/deep-objects-merge.js

UI Kit built on top of Bootstrap 4

const deepObjectsMerge = (target, source) => {
  // Iterate through `source` properties and if an `Object` set property to merge of `target` and `source` properties
  for (const key of Object.keys(source)) {
    if (source[key] instanceof Object) {
      Object.assign(source[key], deepObjectsMerge(target[key], source[key]))
    }
  }

  // Join `target` and modified `source`
  Object.assign(target || {}, source)
  return target
}

export default deepObjectsMerge