regular-redux-undo/src/reducers/changed.js

the plugin of regular-redux to archieve undo and redo

import {get, set} from '../util/immuable';

/**
 * 判断函数获取
 * @param {*} newState 
 * @param {*} oldState 
 */
function getChanged(newState, oldState, undoable) {
  let changed = {};
  return function(path) {
    if (undoable) {
      return get(newState.current, path) !== get(oldState.current, path);
    } else {
      return get(newState, path) !== get(oldState, path);
    }
  }
}

/**
 * 根据路径判断某个state内容是否发生变化的函数
 * @param {Function} reducer
 */
export default function(reducer, undoable = true) {
  return (state, action) => {
    let newState = reducer(state, action);
    newState && (newState.changed = getChanged(newState, state, undoable));
    return newState;
  }
}