Object lifecycle cheatsheet

Firstly, I’d like to apolagize for the lack and timing of these posts. I’ve been busy at work and unfortunately haven’t had the time to write them 😭.

A Javascript object is a standalone entity, with properties and types associated with it. Object properties are basically the same as javascript variables except for they’re attached to objects.

You define a propterty by defining it a value, for example:

1const myCar = new Object();
2myCar.make = 'Ford';

If you define a property but {"don't"} give it a value it becomes undefined, not null. e.g: myCar.color; would return undefined.

To get an item out of an object you can test to see if it has that property, for example, on a project at work, we used this to get a rule's name out of the object

1// The Rule itself
2const rule = {
3  active: true,
4  conditions: [
5    {
6      time: {
7        day: [1, 2, 3, 4],
8        at: '17:30',
9      },
10    },
11  ],
12  uuid: 'some-rule-uuid',
13  consequences: {
14    devices: {
15      '66d5e0ed-5e88-4353-9dd9-318cad3676f9': {
16        'thermostat_setpoint.heat.set': {
17          value: 77,
18        },
19        'thermostat_setpoint.cool.set': {
20          value: 80,
21        },
22      },
23    },
24  },
25  type: 'rule',
26  priority: 1,
27  name: 'test rule',
28};

You can also do if else statements with objects:

1if (cond) var x = { greeting: 'howdy' };

You can even have an object inside another object:

1const myCar = {
2  color: 'red',
3  wheels: 4,
4  engine: {
5    cylinders: 4,
6    size: 2.2,
7  },
8};

Alternatively you can make an object with a constructor function:

1function Car(make, model, year) {
2  this.make = make;
3  this.model = model;
4  this.year = year;
5}
6
7const myCar = new Car('Volvo', 'S40', 2005);