React代码的使用方法教程

本篇内容介绍了"React代码的使用方法教程"的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

1. 仅对一个条件进行渲染

如果需要在条件为 true 时渲染某些内容，而在条件为 false 时不渲染任何内容，不要使 三元表达式，请改用 &&。

?‍♂️ 不推荐示例：

import React, { useState } from 'react'  export const ConditionalRenderingWhenTrueBad = () => {   const [showConditionalText, setShowConditionalText] = useState(false)    const handleClick = () =>     setShowConditionalText(showConditionalText => !showConditionalText)    return (     
       Toggle the text       {/* 三元表达式 */}       {showConditionalText ? 
条件为 True!
 : null}      
   ) }

? 推荐示例：

import React, { useState } from 'react'  export const ConditionalRenderingWhenTrueGood = () => {   const [showConditionalText, setShowConditionalText] = useState(false)    const handleClick = () =>     setShowConditionalText(showConditionalText => !showConditionalText)    return (     
       Toggle the text       {showConditionalText && 
条件为 True!
}     
   ) }

2. 每一个条件都进行渲染

如果需要在条件为 true 时渲染某些内容，而在条件为 false 时渲染其他内容。使用三元表达式!

?‍♂️ 不推荐的示例：

import React, { useState } from 'react'  export const ConditionalRenderingBad = () => {   const [showConditionOneText, setShowConditionOneText] = useState(false)    const handleClick = () =>     setShowConditionOneText(showConditionOneText => !showConditionOneText)    return (     
       Toggle the text       {/* 条件 True 和 False 都要渲染内容 */}       {showConditionOneText && 
条件为 True!
}       {!showConditionOneText && 
条件为 Flase!
}     
   ) }

? 推荐示例：

import React, { useState } from 'react'  export const ConditionalRenderingGood = () => {   const [showConditionOneText, setShowConditionOneText] = useState(false)    const handleClick = () =>     setShowConditionOneText(showConditionOneText => !showConditionOneText)    return (     
       Toggle the text       {showConditionOneText ? (         
The condition must be true!
       ) : (         
The condition must be false!
       )}     
   ) }

3. Boolean props

Props 值为 true 的推荐省略不写。

?‍♂️ 不推荐示例：

import React from 'react'  const HungryMessage = ({ isHungry }) => (   {isHungry ? 'I am hungry' : 'I am full'} )  export const BooleanPropBad = () => (   
            This person is hungry:                
            This person is full:              
 )

? 推荐示例：

import React from 'react'  const HungryMessage = ({ isHungry }) => (   {isHungry ? 'I am hungry' : 'I am full'} )  export const BooleanPropGood = () => (   
            This person is hungry:           {/* 不需要赋值 true，省略 */}          
            This person is full:              
 )

4. String props

Props 值为 String, 使用双引号，不使用花括号或反引号。

?‍♂️ 不推荐示例：

import React from 'react'  const Greeting = ({ personName }) => 
Hi, {personName}!
  export const StringPropValuesBad = () => (   
                  
 )

? 推荐示例：

import React from 'react'  const Greeting = ({ personName }) => 
Hi, {personName}!
  export const StringPropValuesGood = () => (   
                  
 )

5. Event handler functions

如果一个事件函数只接受一个参数，不需要传入匿名函数：onChange={e=>handleChange(e)}，推荐这种写法：onChange={handleChange} 。

?‍♂️ 不推荐示例：

import React, { useState } from 'react'  export const UnnecessaryAnonymousFunctionsBad = () => {   const [inputValue, setInputValue] = useState('')    const handleChange = e => {     setInputValue(e.target.value)   }    return (     <>       Name:        {/* 事件只有一个参数，不需要匿名函数*/}        handleChange(e)} />        ) }

? 推荐示例：

import React, { useState } from 'react'  export const UnnecessaryAnonymousFunctionsGood = () => {   const [inputValue, setInputValue] = useState('')    const handleChange = e => {     setInputValue(e.target.value)   }    return (     <>       Name:                ) }

6. components as props

将组件作为参数传递给另一个组件时，如果该组件不接受任何参数，则无需将该传递的组件包装在函数中。

?‍♂️ 不推荐示例：

import React from 'react'  const CircleIcon = () => (    )  const ComponentThatAcceptsAnIcon = ({ IconComponent }) => (   
     
Below is the icon component prop I was given:
        
 )  export const UnnecessaryAnonymousFunctionComponentsBad = () => (   {/* 组件不需要包装在函数中 */}    } /> )

? 推荐示例：

import React from 'react'  const CircleIcon = () => (    )  const ComponentThatAcceptsAnIcon = ({ IconComponent }) => (   
     
Below is the icon component prop I was given:
        
 )  export const UnnecessaryAnonymousFunctionComponentsGood = () => (    )

7. undefined props

如果参数为 undefined 是允许的，那么不要提供 undefined 作为回退值。

?‍♂️ 不推荐示例：

import React from 'react'  const ButtonOne = ({ handleClick }) => (   Click me )  const ButtonTwo = ({ handleClick }) => {   const noop = () => {}    return Click me }  export const UndefinedPropsBad = () => (   
           alert('Clicked!')} />           alert('Clicked!')} />   
 )

? 推荐示例：

import React from 'react'  const ButtonOne = ({ handleClick }) => (   Click me )  export const UndefinedPropsGood = () => (   
           alert('Clicked!')} />   
 )

8. 设置 state 依赖先前的 state

如果新 state 依赖于先前 state，则始终将 state 设置为先前 state 的函数。可以批处理 React 状态更新。

?‍♂️ 不推荐示例：

import React, { useState } from 'react'  export const PreviousStateBad = () => {   const [isDisabled, setIsDisabled] = useState(false)    const toggleButton = () => setIsDisabled(!isDisabled)    const toggleButton2Times = () => {     for (let i = 0; i < 2; i++) {       toggleButton()     }   }    return (     
                I'm {isDisabled ? 'disabled' : 'enabled'}              Toggle button state       Toggle button state 2 times     
   ) }

? 推荐示例：

import React, { useState } from 'react'  export const PreviousStateGood = () => {   const [isDisabled, setIsDisabled] = useState(false)    {/* 推荐设置为函数 */}   const toggleButton = () => setIsDisabled(isDisabled => !isDisabled)    const toggleButton2Times = () => {     for (let i = 0; i < 2; i++) {       toggleButton()     }   }    return (     
                I'm {isDisabled ? 'disabled' : 'enabled'}              Toggle button state       Toggle button state 2 times     
   ) }

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