The !! operator
To check either a value is truthy or falsey use !! operator you can call this double not or not not operator you can also go with Boolean function here.
console.log(!! 0) // output: false
console.log(!! 1) // output: true
console.log(Boolean(1)) // output: true
console.log(Boolean(0)) // output: false
Convert string → number
Convert string into a number
const string = '101'
console.log(+string) // output: 101
console.log(Number(string)) // output: 101
The reverse method
Use reverse method to reverse the order of array items notice that reverse method mutates the original array.
const numbers = ['1', '2', '3']
console.log(numbers.reverse()) // output: [ "3", "2", "1" ]
The Math.min & max
Find minimum or maximum values from an array using Math.min & Math.max function.
const numbers = [1, 2 ,3, 4, 5]
console.log(Math.min(...numbers)) // output: 1
console.log(Math.max(...numbers)) // output: 5
Merge Arrays
Use spread operator to merge arrays.
const fruits = ['🍎', '🍌']
const vegetables = ['🥔', '🥕']
const food = [...fruits, ...vegetables]
console.log(food) // output: [ "🍎", "🍌" , "🥔", "🥕" ]
The falsey values
In javascript there are nine falsey values.
undefined , null , NaN , 0 , 0n (BigInt 0), -0 ""(empty string),false,document.all
The ternary operator
Ternary operator allows you to write if...else statement in a more compact.
let number = 1
if (number == 1) {
console.log('number is one')
} else {
console.log('number is not one')
}
// Syntax: condition ? exprIfTrue : exprIfFalse (MDN)
console.log(number === 1 ? "number is one" : "number is not one");
Remove duplicates from array
const fruits = ['🍎', '🍊', '🍎', '🍊']
// Method 1:
const filteredFruits = Array.from(new Set(fruits))
console.log(filteredFruits) // output: Array [ "🍎", "🍊" ]
// Method 2:
const filteredFruits = [...new Set(fruits)]
console.log(filteredFruits) // output: Array [ "🍎", "🍊" ]
The map method
Try using map method if you want to manipulate array items map method executes the given function on each element of array and return a new array based on the original array
const numbers = [1, 2, 3, 4, 5]
const mapedNumbers = numbers.map(element => element + 1)
console.log(mapedNumbers) // output: [2, 3, 4, 5, 6]
The includes method
To check that an array contains a certain value or not use includes method.
const hearts = ['🧡', '💙', '🤍']
console.log(hearts.includes('🧡')) // output: true
console.log(hearts.includes('❤️')) // output: false
The filter method
filter arrays based on conditions filter method takes a function as an argument and executes that function on each element of array and returns new array.
const numbers = [1, 5, 6, 7, 4]
const filteredArray = numbers.filter(element => element > 4)
console.log(filteredArray) // output: [ 5, 6, 7 ]
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Happy Coding 😊
Top comments (6)
Thanks @lukeshiru Article is updated !
oh yes, thank you…
Nice tips 🙌
There is no
!!operator - you're just using the!(logical not) operator twice.Also, a shorter way to write the duplicate removal one is:
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