react-native-device-info/lib/module/internal/asyncHookWrappers.js

Get device information using react-native

import { useState, useEffect, useMemo } from 'react';
import { NativeEventEmitter, NativeModules } from 'react-native';

/**
 * simple hook wrapper for async functions for 'on-mount / componentDidMount' that only need to fired once
 * @param asyncGetter async function that 'gets' something
 * @param initialResult -1 | false | 'unknown'
 */
export function useOnMount(asyncGetter, initialResult) {
  const [response, setResponse] = useState({
    loading: true,
    result: initialResult
  });
  useEffect(() => {
    // async function cuz react complains if useEffect's effect param is an async function
    const getAsync = async () => {
      const result = await asyncGetter();
      setResponse({
        loading: false,
        result
      });
    };

    getAsync();
  }, [asyncGetter]);
  return response;
}
export const deviceInfoEmitter = new NativeEventEmitter(NativeModules.RNDeviceInfo);
/**
 * simple hook wrapper for handling events
 * @param eventName
 * @param initialValueAsyncGetter
 * @param defaultValue
 */

export function useOnEvent(eventName, initialValueAsyncGetter, defaultValue) {
  const {
    loading,
    result: initialResult
  } = useOnMount(initialValueAsyncGetter, defaultValue);
  const [result, setResult] = useState(defaultValue); // sets the result to what the intial value is on mount

  useEffect(() => {
    setResult(initialResult);
  }, [initialResult]); // - set up the event listener to set the result
  // - set up the clean up function to remove subscription on unmount

  useEffect(() => {
    const subscription = deviceInfoEmitter.addListener(eventName, setResult);
    return () => subscription.remove();
  }, [eventName]); // loading will only be true while getting the inital value. After that, it will always be false, but a new result may occur

  return useMemo(() => ({
    loading,
    result
  }), [loading, result]);
}
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