Objects are a very commonly used data type in which data is stored using key value pairs. To create an object you can do the following. In the example below we create a beer object with key value pairs for name, ABV, and price. There are multiple ways to instantiate an object as shown below.
let beer = { name: 'Hopadillo', ABV: '6.6%', price: '$2.00' }
// OR
let beer = new Object({ name: 'Hopadillo', ABV: '6.6%', price: '$2.00' })
// OR
function alcohol(name, ABV, price){
this.name = name;
this.ABV = ABV;
this.price = price;
}
let beer = new alcohol('Hopadillo', 'red', '6.6%', '$2.00')
// OR
class Alcohol {
constructor(name, ABV, price) {
this.name = name;
this.maker = maker;
this.engine = engine;
}
}
let beer = new Alcohol('Hopadillo', '6.6%', '$2.00');
1. Object.keys()
This method gets all the keys of an object and puts them in an array. Here is an example using our beer object:
let beerKeys = Object.keys(beer)
// console.log(beerKeys)
// ["name", "ABV", "price"]
2. Object.values()
This method gets all the values of an object and puts them in an array. Here is an example using our beer object:
let beerValues = Object.values(beer)
// console.log(beerValues)
// ["Hopadillo", "6.6%", "$2.00"]
3. Object.entries()
Object.entries() creates a new nested array with each key value pair being converted into an array.
let beerEntries = Object.entries(beer)
// console.log(beerEntries)
// [
// ['name', 'Hopadillo'],
// ['ABV', '6.6%'],
// ['price': '$2.00']
// ]
4. Object.fromEntries()
Object.fromEntries() is used to convert an array into an object. It’s basically the opposite of Object.entries().
let beer = [
['name', 'Hopadillo'],
['ABV', '6.6%'],
['price', '$2.00']
]
let beerFromEntries = Object.fromEntries(beer)
// console.log(beerFromEntries)
// {
// name:"Hopadillo",
// ABV:"6.6%",
// price:"$2.00"
// }
5. Object.assign()
Object.assign() is used to merge multiple objects into one object.
let beer = { name: 'Hopadillo', ABV: '6.6%', price: '$2.00' }
let beerBreweryLocation = { state: 'Texas' }
let beerObj = Object.assign(beer, beerBreweryLocation)
// console.log(beerObj)
// {
// name:"Hopadillo",
// ABV:"6.6%",
// price:"$2.00",
// state:"Texas"
// }
There are of course other methods that you can use on objects, but you likely won’t run into them in the wild too often. To see a more extensive list of methods that can be used on objects check out MDN.
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