JavaScript tips and tricks.

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 ]

Scroll to top button

const button  = document.querySelector('button')

button.addEventListener('click', function () {
  window.scrollTo(0,0)
})

Happy Coding 😊

Comments

[Syed Mohsin Raza]

Thanks @lukeshiru Article is updated !

[Frank Wisniewski]

oh yes, thank you…

[John Palmgren]

Nice tips 🙌

[Jon Randy 🎖️]

There is no !! operator - you're just using the ! (logical not) operator twice.

Also, a shorter way to write the duplicate removal one is:

const filteredFruits = [...new Set(fruits)]