[译] 简单的 React 代码整洁之道｜技术点评

整洁的代码不仅仅是正常运行的代码，更是要求易于阅读、简单易懂、组织整齐。

在本文中，我们将研究八种代码整洁之道。

在阅读这些建议时，要记住这些只是建议！ 如果你不同意它们中的任何一个，那也完全没关系。

以下这些实践，个人觉得对我自己编写 React 代码很有帮助。

让我们开始吧！

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 (
    <div>
      <button onClick={handleClick}>Toggle the text</button>
      {/* 三元表达式 */}
      {showConditionalText ? <p>条件为 True!</p> : null} 
    </div>
  )
}

推荐示例：

import React, { useState } from 'react'

export const ConditionalRenderingWhenTrueGood = () => {
  const [showConditionalText, setShowConditionalText] = useState(false)

  const handleClick = () =>
    setShowConditionalText(showConditionalText => !showConditionalText)

  return (
    <div>
      <button onClick={handleClick}>Toggle the text</button>
      {showConditionalText && <p>条件为 True!</p>}
    </div>
  )
}

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 (
    <div>
      <button onClick={handleClick}>Toggle the text</button>
      {/* 条件 True 和 False 都要渲染内容 */}
      {showConditionOneText && <p>条件为 True!</p>}
      {!showConditionOneText && <p>条件为 Flase!</p>}
    </div>
  )
}

推荐示例：

import React, { useState } from 'react'

export const ConditionalRenderingGood = () => {
  const [showConditionOneText, setShowConditionOneText] = useState(false)

  const handleClick = () =>
    setShowConditionOneText(showConditionOneText => !showConditionOneText)

  return (
    <div>
      <button onClick={handleClick}>Toggle the text</button>
      {showConditionOneText ? (
        <p>The condition must be true!</p>
      ) : (
        <p>The condition must be false!</p>
      )}
    </div>
  )
}

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 }) => (
  <span>{isHungry ? 'I am hungry' : 'I am full'}</span>
)

export const BooleanPropBad = () => (
  <div>
    <span>
      <b>This person is hungry: </b>
    </span>
    <HungryMessage isHungry={true} />
    <br />
    <span>
      <b>This person is full: </b>
    </span>
    <HungryMessage isHungry={false} />
  </div>
)

推荐示例：

import React from 'react'

const HungryMessage = ({ isHungry }) => (
  <span>{isHungry ? 'I am hungry' : 'I am full'}</span>
)

export const BooleanPropGood = () => (
  <div>
    <span>
      <b>This person is hungry: </b>
    </span>
    {/* 不需要赋值 true，省略 */}
    <HungryMessage isHungry />
    <br />
    <span>
      <b>This person is full: </b>
    </span>
    <HungryMessage isHungry={false} />
  </div>
)

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 }) => <p>Hi, {personName}!</p>

export const StringPropValuesBad = () => (
  <div>
    <Greeting personName={"John"} />
    <Greeting personName={'Matt'} />
    <Greeting personName={`Paul`} />
  </div>
)

推荐示例：

import React from 'react'

const Greeting = ({ personName }) => <p>Hi, {personName}!</p>

export const StringPropValuesGood = () => (
  <div>
    <Greeting personName="John" />
    <Greeting personName="Matt" />
    <Greeting personName="Paul" />
  </div>
)

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 (
    <>
      <label htmlFor="name">Name: </label>
      {/* 事件只有一个参数，不需要匿名函数*/}
      <input id="name" value={inputValue} onChange={e => 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 (
    <>
      <label htmlFor="name">Name: </label>
      <input id="name" value={inputValue} onChange={handleChange} />
    </>
  )
}

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 = () => (
  <svg height="100" width="100">
    <circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
  </svg>
)

const ComponentThatAcceptsAnIcon = ({ IconComponent }) => (
  <div>
    <p>Below is the icon component prop I was given:</p>
    <IconComponent />
  </div>
)

export const UnnecessaryAnonymousFunctionComponentsBad = () => (
  {/* 组件不需要包装在函数中 */}
  <ComponentThatAcceptsAnIcon IconComponent={() => <CircleIcon />} />
)

推荐示例：

import React from 'react'

const CircleIcon = () => (
  <svg height="100" width="100">
    <circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
  </svg>
)

const ComponentThatAcceptsAnIcon = ({ IconComponent }) => (
  <div>
    <p>Below is the icon component prop I was given:</p>
    <IconComponent />
  </div>
)

export const UnnecessaryAnonymousFunctionComponentsGood = () => (
  <ComponentThatAcceptsAnIcon IconComponent={CircleIcon} />
)

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 }) => (
  <button onClick={handleClick || undefined}>Click me</button>
)

const ButtonTwo = ({ handleClick }) => {
  const noop = () => {}

  return <button onClick={handleClick || noop}>Click me</button>
}

export const UndefinedPropsBad = () => (
  <div>
    <ButtonOne />
    <ButtonOne handleClick={() => alert('Clicked!')} />
    <ButtonTwo />
    <ButtonTwo handleClick={() => alert('Clicked!')} />
  </div>
)

推荐示例：

import React from 'react'

const ButtonOne = ({ handleClick }) => (
  <button onClick={handleClick}>Click me</button>
)

export const UndefinedPropsGood = () => (
  <div>
    <ButtonOne />
    <ButtonOne handleClick={() => alert('Clicked!')} />
  </div>
)

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 (
    <div>
      <button disabled={isDisabled}>
        I'm {isDisabled ? 'disabled' : 'enabled'}
      </button>
      <button onClick={toggleButton}>Toggle button state</button>
      <button onClick={toggleButton2Times}>Toggle button state 2 times</button>
    </div>
  )
}

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 (
    <div>
      <button disabled={isDisabled}>
        I'm {isDisabled ? 'disabled' : 'enabled'}
      </button>
      <button onClick={toggleButton}>Toggle button state</button>
      <button onClick={toggleButton2Times}>Toggle button state 2 times</button>
    </div>
  )
}

以上就是我推荐的几个写出整洁的 React 代码的实践。

最后，祝你开发愉快！

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