找不到变量 atob

Screen1.js

import React,{useEffect} from 'react'
import {View,Text} from 'react-native'
import * as firebase from 'firebase/app';
import '@firebase/firestore';

const Screen1 = props =>{

    useEffect(() => 
    {
        var dbh = firebase.firestore().collection("Jots").doc("note");
        dbh.set({name:"pradeep"}) //The yellow warning is popped up in this line.
    }); 

    return(
             <View>
                <Text>Title</Text>
             </View>
    )
}

控制台

[Unhandled promise rejection: ReferenceError: Can't find variable: atob]

Stack trace:
  node_modules@firebasefirestoredistindex.cjs.js:23101:0 in <global>
  http://192.168.0.108:19001/node_modules%5Cexpo%5CAppEntry.bundle?platform=android&dev=true&minify=false&hot=false:131203:60 in fromBase64String

我只是按照博览会文档中的指南进行操作，但仍然不知道为什么会出现此问题.对此需要一个明确的解释.还有什么是 atob 变量?

import {decode, encode} from 'base-64'

if (!global.btoa) {  global.btoa = encode }

if (!global.atob) { global.atob = decode }