React 深度学习：React Core

使用 React 必然会重复如下的代码：

import React from 'react';
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通过这段代码，我们从 react 的库中导入了 React，那这个 React 中到底包含哪些东西呢？

import ReactVersion from 'shared/ReactVersion';
import {
  REACT_CONCURRENT_MODE_TYPE,
  REACT_FRAGMENT_TYPE,
  REACT_PROFILER_TYPE,
  REACT_STRICT_MODE_TYPE,
  REACT_SUSPENSE_TYPE,
} from 'shared/ReactSymbols';

import {Component, PureComponent} from './ReactBaseClasses';
import {createRef} from './ReactCreateRef';
import {forEach, map, count, toArray, only} from './ReactChildren';
import {
  createElement,
  createFactory,
  cloneElement,
  isValidElement,
} from './ReactElement';
import {createContext} from './ReactContext';
import {lazy} from './ReactLazy';
import forwardRef from './forwardRef';
import memo from './memo';
import {
  useCallback,
  useContext,
  useEffect,
  useImperativeHandle,
  useDebugValue,
  useLayoutEffect,
  useMemo,
  useReducer,
  useRef,
  useState,
} from './ReactHooks';
import {
  createElementWithValidation,
  createFactoryWithValidation,
  cloneElementWithValidation,
} from './ReactElementValidator';
import ReactSharedInternals from './ReactSharedInternals';
import {enableStableConcurrentModeAPIs} from 'shared/ReactFeatureFlags';

const React = {
  Children: {
    map,
    forEach,
    count,
    toArray,
    only,
  },

  createRef,
  Component,
  PureComponent,

  createContext,
  forwardRef,
  lazy,
  memo,

  useCallback,
  useContext,
  useEffect,
  useImperativeHandle,
  useDebugValue,
  useLayoutEffect,
  useMemo,
  useReducer,
  useRef,
  useState,

  Fragment: REACT_FRAGMENT_TYPE,
  StrictMode: REACT_STRICT_MODE_TYPE,
  Suspense: REACT_SUSPENSE_TYPE,

  createElement: __DEV__ ? createElementWithValidation : createElement,
  cloneElement: __DEV__ ? cloneElementWithValidation : cloneElement,
  createFactory: __DEV__ ? createFactoryWithValidation : createFactory,
  isValidElement: isValidElement,

  version: ReactVersion,

  unstable_ConcurrentMode: REACT_CONCURRENT_MODE_TYPE,
  unstable_Profiler: REACT_PROFILER_TYPE,

  __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactSharedInternals,
};

// Note: some APIs are added with feature flags.
// Make sure that stable builds for open source
// don't modify the React object to avoid deopts.
// Also let's not expose their names in stable builds.

if (enableStableConcurrentModeAPIs) {
  React.ConcurrentMode = REACT_CONCURRENT_MODE_TYPE;
  React.Profiler = REACT_PROFILER_TYPE;
  React.unstable_ConcurrentMode = undefined;
  React.unstable_Profiler = undefined;
}

export default React;
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结构

React Core，结构图如下

链接

• ReactBaseClasses
• ReactElement
• ReactHooks
• ReactContext
• ReactCreateRef
• forwardRef
• ReactLazy
• memo
• Children

React Element:

• createElement

• cloneElement

• createFactory

• isValidElement

• ReactElementValidator 用于开发环境

  • createElementWithValidation
  • cloneElementWithValidation
  • createFactoryWithValidation

React Symbol：

• Fragment
• StrictMode
• Suspense

其他：

• version

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转载于:https://juejin.im/post/5d0ecaecf265da1bab29b7ef