这个例子网上比较多,基本上详解setState机制的用的都是这个,正解是0,0,2,3 一个例子一般满足不了我,于是我就多试了几个,再看下一个: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 componentDidMount() { this.setState({ index: this.state.index + 1 }); console.log(this.state.index);...
the component that renders the input (aka the form component) saves that in itsstate:(翻译:这很好,但是这种输入的input值必须被存放在state中。通常,我们在使用表单组件时,是需要将其值保存在自身相关的state中,作者暗示还有其他保存方式)
在满足某个条件时,通过修改showAnotherComponent的值为true,可以触发组件的重新渲染,从而呈现另一个组件。 以下是一个简单的示例代码: 代码语言:txt 复制 import React, { useState } from 'react'; function MyComponent() { const [showAnotherComponent, setShowAnotherComponent] = useState(false); const...
pop,shift,splice方法都不会改变原址;newWords.push(this.ref.current.value);//如果在子组件使用了PureComponent浅比较words的值,nextProps.words === this.props.words//所以不会引起子组件Counter的render方法调用this.setState({
React(三) 修改状态 【数据驱动视图思想】 通过setState修改状态 作用： 修改state 更新ui 语法：this....
First of all, thank you for giving us React. I have a custom hook that uses setState(primitiveValue) that will re render the component when primitiveValue did not change React version: 17.0.1 The current behavior code sandbox when pressi...
A component can have an initial state set, access it, and update it. In the code block below, we are setting the component’s initial state. This is done through the constructor method:import React, { Component } from 'react'; class Food extends Component { constructor(props) { super(...
🐛 Bug Report React show a warning when a function component is updated during another component's render phase. https://fb.me/setstate-in-render To Reproduce The codesandbox to reproduce the issue: Open console. Click on "en" Expected be...
import{Component,setState}from"react";classElementextendsComponent{constructor(props){super(props);this.state={value:1};}handleClick(){this.setState({value:2});}render(){return(Value is:{this.state.value})}}export{Element} Theoretically, when we run our code, we should get a div in the...
updateClassComponent 在setState更新阶段,updateClassInstance对该组件实例属性进行更新, 如执行updateQueue链更新其对应的state变更的值。 state更新完成后, 需要生成新的虚拟DOM这一系列的过程在finishClassComponent。 render完成后会返回组件的根节点fiber作为下一次迭代的workInProgress ...