选择器在组件渲染之前执行

Question

我的选择器在渲染它们映射的组件之前执行。为什么会这样？例如在下面的代码中，messages 选择器在 Component 呈现之前执行。谢谢！

import React from 'react';
import {connect} from 'react-redux';
import * as selectors from './selectors';

const Component = ({message}) => (
  <div>
    {message}
  </div>
);

const mapStateToProps = (state, props) => ({
  message: selectors.message(state, props),
});

export default connect(mapStateToProps)(Component);

Answer 1

在React-Redux v5中，实现mapState的内部选择器是initialized in the wrapper component constructor, and is called right away as part of that process.

在 React-Redux v6 中，内部选择器是 created in the wrapper component constructor, but called during the render process。