如何使用React从Firebase检索字段值？

Question

I am trying to learn Firebase. I made a very simple ReactApp along with a very simple database in Firebase. I am so beyond confused as to how to access a field's value. I'm sure this is an extremely simple question, but somehow, I am missing how to find the solution.

My database looks as such: https://imgur.com/a/3LczlwI

I really would like to know how to access the "Speed" field value.

I have tried

const db = firebase.database.ref();
const speedRef = 
db.child('react').child('mySpeed').once('value').then(snap =>{
  if (snap.val()){
    this.setState({ speed: snap.val().speed });
  } else {
    console.log('error');
  }
})

Along with

const speedRef = firebase.database().ref().child('mySpeed').child('speed');
speedRef.on('value', snap => {
  this.setState({ speed: snap.val() });
})

To no avail. I really hope someone can help me understand this. Thank you in advance.

Answer 1

*try to use this: *

 const react = firebase.database().ref("react"); react.child("mySpeed").child("speed").once("value").then(data => { if(data.val() !== null){ console.log(data.val()); } });