JAVASCRIPT OBJECT & ITS INTERNAL REPRESENTATION

OBJECT

Objects are same in all programming languages i.e they represent real-world things that we want to represent inside our programs with characteristics/properties and methods. In JavaScript Objects are kind of String/Number  Index Array represented inside curly brackets

Var obj = {

1: “NAME”,

"Maths" :100

}

KEY VALUE PAIR

In the above example obj is an object with 2 properties with key as 1 and Maths and value as Name and 100.Here the index are called as KEY.KEY :VALUE pair together called as entries

Object literals are a comma-separated list of key-value pairs wrapped in curly braces. Object literal property values can be of any data type, including array literals, functions, nested object literals or primitive data type.

Obj Values  in the above can be accessed via Dot notation i.e obj.1 ,obj.Maths  or via a square bracket notation i.e obj[1] ,obj[“Maths”]

Object.assign() METHOD

As we discussed earlier in JavaScript Objects are kind of String/Number  Index Array represented inside curly brackets.So with the help of object.assign() method we can convert the array into object.

var arr = [“a”,”b”,”c”]

var obj = Object.assign({},arr}

// obj = {0:”a”, 1:”b”,2:”3”}

In the above example array indexes are converted as key for objects.

 

Object.assign method also helps to merge the objects

const obj1 = { a: 1 };

const obj2 = { b: 2 };

const obj3 = { c: 3 };

const obj = Object.assign({},obj1, obj2, obj3);

console.log(obj); // { a: 1, b: 2, c: 3 }

console.log(obj1);  // { a: 1, b: 2, c: 3 }, target object itself is changed.

 

const obj1 = { a: 1, b: 1, c: 1 };

const obj2 = { b: 2, c: 2 };

const obj3 = { c: 3 };

const obj = Object.assign({}, obj1, obj2, obj3);

console.log(obj); // { a: 1, b: 2, c: 3 }

 

To get all the key in separate array

Object.Keys(obj)

To get all the key in separate array

Object.Values(obj)

To get all the key value pair in array

Object.entries(obj)