Why does this script show error? [Firebase][Web]

Question

//initialize firebase

After initializing firebase,

var database = firebase.database();
var ref = database.ref('entry');
var data = {
name : 'Arb',
age : 16
};
ref.push(data);

Why does this script show error??
Help please!

Answer 1

Coder bro it shows permission denied error though!

Answer 2

Coder I have changed the rule to public !! But still showing it !!

Answer 3

Coder ok bro!