无法从firebase中存储的字符串中删除最后一个字符

const firebase = require('firebase/app');
require('firebase/database');

// 初始化Firebase
const firebaseConfig = {
  apiKey: "YOUR_API_KEY",
  authDomain: "YOUR_AUTH_DOMAIN",
  databaseURL: "YOUR_DATABASE_URL",
  projectId: "YOUR_PROJECT_ID",
  storageBucket: "YOUR_STORAGE_BUCKET",
  messagingSenderId: "YOUR_MESSAGING_SENDER_ID",
  appId: "YOUR_APP_ID"
};

firebase.initializeApp(firebaseConfig);

// 读取数据
const database = firebase.database();
const dataRef = database.ref('your_data_path');

dataRef.once('value', (snapshot) => {
  const data = snapshot.val();
  if (data) {
    console.log('Data retrieved:', data);
    // 处理数据
    const processedData = removeLastCharacter(data);
    console.log('Processed Data:', processedData);
  } else {
    console.log('No data available');
  }
});

function removeLastCharacter(str) {
  if (typeof str !== 'string' || str.length === 0) {
    return str;
  }
  return str.slice(0, -1);
}

dataRef.on('value', (snapshot) => {
  const data = snapshot.val();
  if (data) {
    console.log('Data updated:', data);
    // 处理数据
    const processedData = removeLastCharacter(data);
    console.log('Processed Data:', processedData);
  } else {
    console.log('No data available');
  }
});