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: '******************' }
*/
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