Vfrdtyky

I am reading about getters and setters in javascript. I would like to know if there is a difference between this two ways of coding with and without setters

first way, without setters.

>obj1 = {

    arr: ;

 }

>obj1.arr.push('first')

>obj1.arr

[ 'first' ]

Second way, with setters.

>obj2 = {

    set add(data) {

        this.arr.push(data);

    },

    arr: 

 }

>obj2.add = 'first'

>obj2.arr

[ 'first' ] 

The setter syntax in your example does not really prevent the client code to still add a value using the direct push call as in the first code block. So the difference is that you just added another way to do the same thing.

To make a fair comparison, you would have to define the same method in both alternatives: once as a normal method and once as a setter method, and then the difference is just the syntax how the argument is passed to the method, either with obj.add('first') or obj.add = 'first'.

In this actual case I would vote against the setter, because it gives the false impression that if you "assign" another value, the first assigned value is overwritten:

obj.add = 'first';

obj.add = 'second';

... but obviously this is not the case: both values exist in the object now.

First, The set Syntax bind an object property to a defined function. In this particular example, there is no difference between two codes, but let's say for example you want to check if the value is negative before adding it to the array, so you can use set to Encapsulate that behavior.

So basically, using setter is only to add additional encapsulated behavior to the functions of the objects.

The way of accessing the array index called bracket notation. it is equal to dot notation, except the bracket notation allows you to set new properties to objects or arrays dynamically.

Hope this help you.

I think difference only about "how it looks like". Using setters it's closest way for understanding for people who came to js from object oriented languages.

The getter/setter property is not the same as "normal" instance property, one is called "named data property", the other is called "named accessor property".

Please let met quote below part of documents from the ECMAScript 5.1.

https://www.ecma-international.org/ecma-262/5.1/#sec-8.10.1

An Object is a collection of properties. Each property is either a
named data property, a named accessor property, or an internal
property:

A named data property associates a name with an ECMAScript language
value and a set of Boolean attributes.

A named accessor property associates a name with one or two accessor
functions, and a set of Boolean attributes. The accessor functions are
used to store or retrieve an ECMAScript language value that is
associated with the property.

An internal property has no name and is not directly accessible via
ECMAScript language operators. Internal properties exist purely for
specification purposes.

There are two kinds of access for named (non-internal) properties: get
and put, corresponding to retrieval and assignment, respectively.

And

If the value of an attribute is not explicitly specified by this
specification for a named property, the default value defined in Table
7 is used.