In this lesson we'll take a stateful React component and look at how we can refactor our setState calls to use an updater function and then leverage Ramda's evolvefunction to make our updater function a reusable utility that isn't tied to the React A…

React & update state with props & Object.assign Object.assign({}, oldObj, newObj) https://reactjs.org/docs/react-component.html#unsafe_componentwillreceiveprops Object.assign( previousState, {quantity: state.quantity + 1}, {quantity: state.quantit…

getDerivedStateFromProps is lifecycle hook introduced with React 16.3 and intended as a replacement for componentWillReceiveProps. It is invoked after a component is instantiated as well as when it receives new props. It should return an object to up…

react 中state与props 1.state与props props是只读属性,只有在组件被实例化的时候可以赋值,之后的任何时候都无法改变该值.如果试图修改该值时,控制台会报错 only read. state与props正好相反,state中保存可变的值.通过this.setState()方法修改对应的值.使用state必须通过es6继承React.Component 类(官方推荐写法),并在构造函数内进行初始化. export default class BoubleBind ext…

In this lesson, we'll refactor a React component to use Ramda lenses to update our component state. We'll create a lens to focus on the property we want to target and use over to apply the existing state value to a utility function and we'll get back…

In React, components manage their own state. In this lesson, we'll walk through building a component which manages it's own state as well as using TextInput and TouchableHighlight to handle touch events. import React, { Component, PropTypes } from 'r…

State is used for properties on a component that will change, versus static properties that are passed in. This lesson will introduce you to taking input within your React components. Properties vs. State When you think of properties, you should be t…

一.state 1.state的作用 state是React中组件的一个对象.React把用户界面当做是状态机,想象它有不同的状态然后渲染这些状态,可以轻松让用户界面与数据保持一致. React中,更新组件的state,会导致重新渲染用户界面(不要操作DOM).简单来说,就是用户界面会随着state变化而变化. 2.state工作原理 常用的通知React数据变化的方法是调用setState(data,callback).这个方法会合并data到this.state,并重新渲染组件.渲染完成后,…

React is great for diffing between Virtual-DOM and rendering it to the dom. It also offers a naïve solution for diffing state in terms of setState. However it is slightly verbose and not easy to scale. MobX offers a very simple and effective solution…

如果你看过React的官方文档,就会对怎么给局部state赋值有一定的了解.如下代码: class Test extends React.Component { constructor(props) { super(props); this.state = { name:'李磊' }; // 为了在回调中使用 `this`,这个绑定是必不可少的 this.handleClick = this.handleClick.bind(this); } handleClick(){ this.setSta…