js-array-8-must-know.md

• 8 Must Know JavaScript Array Methods
  • 1. filter
  • 2. map
  • 3. find
  • 4. forEach
  • 5. some
  • 6. every
  • 7. reduce
  • 8. include

8 Must Know JavaScript Array Methods

const items = [
    { name: 'Bike', price: 100 },
    { name: 'TV', price: 200 },
    { name: 'Album', price: 10 },
    { name: 'Book', price: 5 },
    { name: 'Phone', price: 500 },
    { name: 'Computer', price: 1000 },
    { name: 'Keyboard', price: 25 }
]

1. filter

const filteredItems = items.filter((item) => {
    return item.price <= 100
})

console.log(filteredItems)

[
  { name: 'Bike', price: 100 },
  { name: 'Album', price: 10 },
  { name: 'Book', price: 5 },
  { name: 'Keyboard', price: 25 }
]

2. map

[
  'Bike',     'TV',
  'Album',    'Book',
  'Phone',    'Computer',
  'Keyboard'
]

3. find

find a single object in an array

const foundItem = items.find((item) => {
    return item.name === 'Book'
})

{ name: 'Book', price: 5 }

4. forEach

items.forEach((item) => {
    console.log(item.price)
})

100
200
10
5
500
1000
25

5. some

return true if any items in array satisfy some condition.

const hasInexpensiveItems = items.some((item) => {
    return item.price <= 100
})

true

6. every

return true if all items in array satisfy some condition

const allInexpensiveItems = items.every((item) => {
    return item.price <= 100
})

false

7. reduce

const total = items.reduce((currentTotal, item) => {
    return item.price + currentTotal
}, 0)

1840

8. include

const numbers = [1,2,3,4,5]
const includesTwo = numbers.includes(2)
console.log(includesTwo)

true