@angular-redux/store/src/utils/set-in.ts

Angular 2 bindings for Redux

/**
 * Sets a deeply-nested property value from an object, given a 'path'
 * of property names or array indices. Path elements are created if
 * not there already. Does not mutate the given object.
 *
 * @hidden
 */
export const setIn = (
  obj: Object,
  [ firstElem, ...restElems ]: (string | number)[],
  value): Object => ({
    ...obj,
    [firstElem]: restElems.length === 0 ?
      value :
      setIn(obj[firstElem] || {}, restElems, value)
    });