react-redux/lib/hooks/useSelector.js

Official React bindings for Redux

"use strict";

exports.__esModule = true;
exports.createSelectorHook = createSelectorHook;
exports.useSelector = void 0;

var _react = require("react");

var _extra = require("use-sync-external-store/extra");

var _useReduxContext = require("./useReduxContext");

var _Context = require("../components/Context");

const refEquality = (a, b) => a === b;
/**
 * Hook factory, which creates a `useSelector` hook bound to a given context.
 *
 * @param {React.Context} [context=ReactReduxContext] Context passed to your `<Provider>`.
 * @returns {Function} A `useSelector` hook bound to the specified context.
 */


function createSelectorHook(context = _Context.ReactReduxContext) {
  const useReduxContext = context === _Context.ReactReduxContext ? _useReduxContext.useReduxContext : () => (0, _react.useContext)(context);
  return function useSelector(selector, equalityFn = refEquality) {
    if (process.env.NODE_ENV !== 'production') {
      if (!selector) {
        throw new Error(`You must pass a selector to useSelector`);
      }

      if (typeof selector !== 'function') {
        throw new Error(`You must pass a function as a selector to useSelector`);
      }

      if (typeof equalityFn !== 'function') {
        throw new Error(`You must pass a function as an equality function to useSelector`);
      }
    }

    const {
      store
    } = useReduxContext();
    const selectedState = (0, _extra.useSyncExternalStoreExtra)(store.subscribe, store.getState, // TODO Need a server-side snapshot here
    store.getState, selector, equalityFn);
    (0, _react.useDebugValue)(selectedState);
    return selectedState;
  };
}
/**
 * A hook to access the redux store's state. This hook takes a selector function
 * as an argument. The selector is called with the store state.
 *
 * This hook takes an optional equality comparison function as the second parameter
 * that allows you to customize the way the selected state is compared to determine
 * whether the component needs to be re-rendered.
 *
 * @param {Function} selector the selector function
 * @param {Function=} equalityFn the function that will be used to determine equality
 *
 * @returns {any} the selected state
 *
 * @example
 *
 * import React from 'react'
 * import { useSelector } from 'react-redux'
 *
 * export const CounterComponent = () => {
 *   const counter = useSelector(state => state.counter)
 *   return <div>{counter}</div>
 * }
 */


const useSelector = /*#__PURE__*/createSelectorHook();
exports.useSelector = useSelector;