Objects

Defining an object:

let course = new Object();

course.title = "Learning Javascript";
course.level = "Beginner";
course.published = true;

console.log(course);

{title: "Learning Javascript", level: "Beginner", published: true}

We can delete a property by the following way:

delete course.level

There is another shorthand:

let course = new Object();

let course = {
    title: "Learning Javascript",
    level: "Beginner",
    published: true,
}

Apart from the object properties, we can also have object methods, to do something on the data. Methods are functions.

let course = new Object();

let course = {
    title: "Learning Javascript",
    level: "Beginner",
    published: true,
    views: 0,
    updateViews: function(){
        return ++course.views;
    }
}

You can try printing out course.updateViews() repeatedly.

Object constructor

These are sort of templates we can reuse.

function Course(title, level, published, views) {
    this.title = title;
    this.level = level;
    this.published = published;
    this.views = views;
    this.updateViews = function() {
        return ++this.views;
    };
}

let course01 = new Course("Learning Javascript", "Beginner", true, "0");

console.log(course01)

Course {title: "Learning Javascript", level: "Beginner", published: true, views: "0", updateViews: function}

note

Often we might need to work with external objects and they might have strange naming convention, like fonts:serif. In such cases, javascript will return error if you use dot notation course.fonts:serif. There is a bracket notation to call properties as well course["fonts:serif"].