Non-primitive data types like objects can be stored and copied by reference.
See the examples below:
Primitive data type
const name = 'Bello';
const myName = name;
console.log(myName); // Bello
Non-primitive data type
const obj = { name: 'Bello', favNum: 9 };
const person = obj; // copy the reference
console.log(person); // { name: 'Bello', favNum: 9 }
console.log(person.favNum); // 9
The object { name: 'Bello', favNum: 9 } is assigned to the variable obj to store its address in memory. Think of obj like a sheet of paper with an address in it. That is, person copied the reference to the object obj.
Accessing the value of the object (person.favNum) looks for the address of obj through person
The object
objitself is not duplicated
We can also modify the object content.
const obj = { name: 'Bello', favNum: 9 };
const person= obj; // copy the reference
console.log(person); // { name: 'Bello', favNum: 9 }
person.favNum = 69;
console.log(person); // { name: 'Bello', favNum: 69 }
Comparison by reference
Two objects are equal only if they are the same object.
const a = {};
const b = a; // copy the reference
console.log(a == b); // true, both variables reference the same object
console.log(a === b); // true
Since a and b reference the same object, thus they are equal.
Here also two independent objects are not equal, even though they look alike (both are empty):
const a = {};
const b = {}; // two independent objects
console.log(a == b); // false
Happy coding!
TechStack | Domain
- Purchase a
.comdomain name as low as $9.99. - Purchase a
.netdomain name as low as $12.99. - Get cheaper domain names as low as $3.
- Build a website with ease.