Objects in JavaScript are collections of Key/Value pairs. The values can consist of properties and methods. This post will go over important built-in object methods.

Object.create()

Used to create a new object and link it to the prototype of an existing object.

const person = {
     isHuman: false,
     printIntroduction: function() {
          console.log('My name is ${this.name}. Am I a human? ${this.isHuman}')
     }
}

const me = Object.create(person)

me.name = 'Mursal'
me.isHuman = true

me.printIntroduction()
// Expected Output: "My name is Mursal. Am I a human? true"

Object.keys() and Object.values()

Object.keys(): Creates an array containing the keys of an object
Object.values(): Creates an array containing the values of an object

const num = {
     one: 1,
     two: 2,
     three: 3
}

console.log(Object.Keys(num)) // ['one', 'two', 'three']
console.log(Object.Values(num)) // [1, 2, 3]

Object.entries()

Used to create a nested array of the key/value pairs of an object

const num = {
     one: 1,
     two: 2,
     three: 3
}

console.log(Object.entries(num))

/*
     Expected Output
     [['one', 1], ['two', 2], ['three', 3]]
*/

Object.assign()

It is used to copy values from one object to another.

const name = {
     firstName: 'Mursal',
     lastName: 'Furqan'
}

const details = {
     job: 'Software Engineer',
     country: 'Italy'
}

// Merge the object
const character = Object.assign(name, details)

console.log(character)

/* 
     Expected Output
     {
          firstName: 'Mursal',
          lastName: 'Furqan',
          job: 'Software Engineer',
          country: 'Italy'
     }
*/

Object.freeze()

Prevents modification to properties and values of an object, and prevents properties from being added or removed from an object

const user = {
     username: 'mursalfurqan',
     password: 'thisisalwayssecret'
}

// Freeze the object
const newUser = Object.freeze(user)

newUser.password = '*******************'
newUser.active = true

console.log(newUser)

/* 
     Expected Output
     { username: 'something', password: 'thisisalwayssecret' }
*/

Object.seal()

Prevents new properties from being added to an object, but allows the modification of existing properties.

const user = {
     username: 'mursalfurqan',
     password: 'thisisalwayssecret'
}

// Seal the object
const newUser = Object.seal(user)

newUser.password = '*******************'
newUser.active = true

console.log(newUser)

/* 
     Expected Output
     { username: 'something', password: '******************' }
*/

Let's explore Objects Methods in JavaScript