我应该用哪种方式导入 React？

Question

I'm not sure which way I' supposed to import React in my React Native app. If I need to use a hook like useState should I import React with: import React, { useState } from 'react'; , import { useState } from 'react'; , import * as React from 'react'; , or import * from 'react'; ? If I don't need any hooks should I use: import React from 'react'; , import 'react'; , import * as React from 'react'; , or import * from 'react'; ?

Answer 1

As of react version 17+, you don't need to import React from 'react' anymore. Read more about the JSX transformation.

Hooks are named exports, so you need to import hooks as:

import {useState, useEffect /* and others */} from 'react'

If you are using a react version below 17, you need to import React . Since React would be a default import these are all refer to the same thing:

import React from 'react'
import * as React from 'react'

So you should do import React, {/* hooks you are using */} from 'react' .

You can even do import * as Whatever from 'react' , since it is not a named export.