react-redux中connect中的mapDispatchToProps疑惑

Question

代码一：

import { addTodo } from './actionCreators'
import { bindActionCreators } from 'redux'

function mapStateToProps(state) {
  return { todos: state.todos }
}

function mapDispatchToProps(dispatch) {
  return bindActionCreators({ addTodo }, dispatch)
}

export default connect(mapStateToProps, mapDispatchToProps)(TodoApp)

代码二：

import { addTodo } from './actionCreators'

function mapStateToProps(state) {
  return { todos: state.todos }
}

const mapDispatchToProps = {
  addTodo
}

export default connect(mapStateToProps, mapDispatchToProps)(TodoApp)

以上两段代码的作用都是注入 todos 和特定的 action 创建函数，有一点疑惑的地方
代码一中调用了bindActionCreators而代码二中没有调用，两段代码出来的效果都是一样的。
请问bindActionCreators的作用是什么？

Answer 1

function bindActionCreator(actionCreator, dispatch) {
  return (...args) => dispatch(actionCreator(...args));
}

/*
 * @param actionCreators
 * @param dispatch
 * @return {actionKey: (...args) => dispatch(actionCreator(...args))}
 */
export default function bindActionCreators(actionCreators, dispatch) {
  return mapValues(actionCreators, actionCreator =>
    bindActionCreator(actionCreator, dispatch)
  );
}

bindActionCreators部分源码，再里面调用了dispatch方法