Introduction
In this article, we will understand Objects in Javascript. Before we start, Let's understand the objective of this demonstration, which tells what exactly will be covered in this article.
- object.keys()
- object.values()
- object.entries()
- object.create()
- object.assign()
- object.seal()
So, Let's get started,
Objects in JavaScript
An object is a standalone entity with properties and types.
Syntax
const object = {
property1:value1,
property2:value2.....
propertyN:valueN
};
Example
const person = {
name: 'vishal',
age: 32,
gender: 'male',
};
object.keys()
A simple way to iterate over an object and return all of the object's keys.
Syntax
Object.keys(object);
Example
const employee = {name: "Vishal", age: 32, designation: "Architect", level: 5};
console.log(Object.keys(employee));
// Result:
// [object array] (4)
// ["name", "age", "designation", "level"]
![Object.keys(object)]()
object.values()
Iterates over the object and returns the object's values!
Syntax
Object.values(object);
Example
const employee = {name: "Vishal", age: 32, designation: "Architect", level: 5};
console.log(Object.values(employee));
// Result:
// [object array] (4)
// ["Vishal", "32", "Architect", "5"]
![Object.values(object)]()
object.entries()
Takes an object and returns its own enumerable string-keyed property[key, value] pairs of the object.
Syntax
Object.entries(object);
Example
const employee = {name: "Vishal", age: 32, designation: "Architect", level: 5};
console.log(Object.entries(employee));
// Result:
['name', 'Vishal']
['age', 32]
['designation','Architect']
['level','5']
![Object.entries(object)]()
object.create()
Create a new object using an existing object as the prototype of the newly created object.
Syntax
Object.create(prototype_object, propertiesObject)
Example
const employee = {
name: "Vishal",
display: function() {
console.log('Name: ' + this.name);
}
}
let newEmployee = Object.create(employee);
newEmployee.name = 'Kunal';
// log both objects
newEmployee.display(); // display new name
employee.display(); // dispal old name
![Object.create(object)]()
object.assign()
Copies all enumerable and own properties from the source object to the target object. It returns the target object. It is also called shallow copy.
Syntax
Object.assign(target, ...sources);
Example
const person = {
name: 'vishal',
age: 32,
gender: 'male',
};
const job = {
designation: 'developer',
salary: 1000,
};
Object.assign(person, job);
![object.assign(target,sources)]()
object.seal()
Seal an object which prevents new properties from being added to it and marks all existing properties as nonconfigurable.
Syntax
Object.seal(object)
Example
const car = {
price: 15000
};
Object.seal(car);
car.price = 18000; // value changed
console.log(car.price);
// Result : 18000
delete car.price;
console.log(car.price); // can't delete when sealed.
// Result: 18000
![Object.seal(object)]()
Summary
In this article, I have tried to cover how to use Objects in JavaScript, which are mostly used in our development.
Reference