To learn JavaScript, we must learn the basics.
In this article, we’ll look at the most basic parts of the JavaScript language.
We can add methods to constructors or classes.
For example, we can write:
class Plan {
constructor(name, price, space, pages) {
this.name = name;
this.price = price;
this.space = space;
this.pages = pages;
}
calcAnnualPrice() {
return this.price * 12;
}
}
We add the calcAnnualPrice
method to return the value of this.price * 12
.
this
is the class instance, which is the object that’s created and returned when we invoke the Plan
class.
So we get the price
property from the object we create from the class and multiply it by 12.
To invoke the constructor and call the method on the created object, we can write:
const plan = new Plan('basic', 3, 100, 10)
console.log(plan.calcAnnualPrice())
We invoke the Plan
constructor with the new
keyword.
Then we call calcAnnualPrice
on the plan
object to get the annual price.
The class syntax is just syntactic sugar on top of prototype inheritance.
The calcAnnualPrice
method is just a property of the Plan
‘s prototype
property.
The prototype
is the prototype of the Plan
class, which is the object that it inherits from.
If we log the value of Plan.prototype.calcAnnualPrice
:
console.log(Plan.prototype.calcAnnualPrice)
we see the code of the calcAnnualPrice
method logged.
#javascript #technology #programming