Javascript references

gistfile1.js

var day = {name: 'day 1', rooms: [1, 2, 3]};

// create a separate var pointing to the same room list
var rooms = day.rooms;

day.rooms === rooms; // true

// delete the rooms list from the day object
delete day.rooms;

// room list should still point to the list
rooms; // [1, 2, 3, 4]