I am new to firebase but have been using java script for a while but i don't understand what snap => does and why its used

Question

I started using firebase and I came across the snap => when passing value:

var rh = document.getElementById('rh'); 
var dbref = firebase.database().ref('text') 
dbref.on('value', snap => rh.innerText = snap.val())

I would like to understand what it does and what is the use of it.

Answer 1

It's just simple syntax for a function. Instead of:

function f(snap) {
    return "hello world";
}
const c = f;

You can write the following to make it easier to read:

const c = snap => return "hello world";

Now c is a constant that holds the function above.