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JavaScript Object-Oriented JavaScript Getters and Setters Getters

Posted by Dávid Molnár
Dávid Molnár
27,081 Points

[JavaScript] get vs simple function

Hello everyone
I wonder if there's any difference between get and a simple function like:

class Example () {
 constructor() {}
 get activity() {
   return "sleeping";
 }

 isEating() {
  return true;
 }
}

Both are very simple but I think it is enough to show my concern. As I see in the curses both can be used to return a value no matter if it's more complicated or not. Same goes for "set". I am sure there's a good reason why get / set exists in JavaScript, could you explain me please? Or it's simply because they can have the same name?

3 Answers

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

The main difference between getters and other methods is how they are accessed. Methods are called by adding parentheses after their names and can take arguments, but getters are called just by naming them (and can't have arguments). So in usage, getters seem to be more like properties than methods.

For examples, using your class (after removing the parentheses from the class definition line):

instanceOfExample = new Example();

let eating = instanceOfExample.isEating();  // the function is invoked using parentheses
let status = instanceOfExample.activity;    // the getter is invoked just by naming it
olu adesina
olu adesina
23,007 Points
olu adesina
olu adesina
23,007 Points

thanks Steven this explanation makes perfect sense

Kirt Perez
Kirt Perez
7,374 Points

What is the advantage of this though? Removing just a parentheses?

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

Essentially, yes, but it's more about the conceptual aspect of having it behave like a property instead of a method.

bobdeei
bobdeei
8,575 Points
bobdeei
bobdeei
8,575 Points

Hi Steven, I understand what you mean in the code. But I have another concern that seems to be like David's. What's the real application or the real reason behind the get function? We won't see the get function if you log the object because it's not attached to the object, but how does this benefit our code?

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

It allows you to create a "computed property" where some code is necessary to return the value. This allows you to have the data represented by a property and reserve methods for things that cause changes.

Van Tran Huu
Van Tran Huu
16,694 Points
Van Tran Huu
Van Tran Huu
16,694 Points

the get method seems working like a computed property than a method. A computed property is a 'dynamic' property (data) which is computed based on some fixed properties, I suppose!