DEV Community

Cover image for 20+ Handy JavaScript Functions to Simplify Your Code | JavaScript Tutorial
Rahul Sharma
Rahul Sharma

Posted on

20+ Handy JavaScript Functions to Simplify Your Code | JavaScript Tutorial

#javascript #webdev #programming #tutorial

JavaScript is a functional programming language, and functions play a crucial role. They allow you to encapsulate reusable code and perform specific tasks. Here are some quick examples of functions that can make your life easier:

Regular function 



function sum(a, b) {
  return a + b;
}
Enter fullscreen mode Exit fullscreen mode

Function expression 



const sum = function (a, b) {
  return a + b;
};
Enter fullscreen mode Exit fullscreen mode

Arrow function 



const sum = (a, b) => {
  return a + b;
};
// OR
const sum = (a, b) => a + b;
Enter fullscreen mode Exit fullscreen mode

Generator function 



function* indexGenerator() {
  let index = 0;
  while (true) {
    yield index++;
  }
}
const g = indexGenerator();
console.log(g.next().value); // => 0
console.log(g.next().value); // => 1
Enter fullscreen mode Exit fullscreen mode

Create an array of numbers from 1 to n 



const range = (n) => Array.from({ length: n }, (_, i) => i + 1);
console.log(range(10)); // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Enter fullscreen mode Exit fullscreen mode

Create an array of numbers from 1 to n with a step 



const range = (n, step = 1) => Array.from({ length: n }, (_, i) => i * step);
console.log(range(10, 2)); // [1, 3, 5, 7, 9]
Enter fullscreen mode Exit fullscreen mode

Create an array and fill it with a value 



const fill = (len, value) => Array(len).fill(value);
console.log(fill(3, 0)); // [0, 0, 0]
Enter fullscreen mode Exit fullscreen mode

Shuffling an array 



const shuffleArray = (arr) => arr.sort(() => 0.5 - Math.random());
console.log(shuffleArray([1, 2, 3, 4])); // [3, 2, 1, 4]
Enter fullscreen mode Exit fullscreen mode

Remove Duplicated from Array 



const removeDuplicated = (arr) => [...new Set(arr)];
console.log(removeDuplicated([1, 2, 3, 3, 4, 4, 5, 5, 6])); // Result: [ 1, 2, 3, 4, 5, 6 ]

const removeDuplicate = (arr) =>
  Object.values(arr.reduce((a, b) => (a[b] ? a : { ...a, [b]: b }), {}));
console.log(removeDuplicate([1, 2, 3, 3])); // Result: [ 1, 2, 3, ]
Enter fullscreen mode Exit fullscreen mode

Generate random number 



const random = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;
console.log(random(1, 10)); // Result: 1 ~ 10
Enter fullscreen mode Exit fullscreen mode

Find largest numbers 



const findLargest = (arr) => arr.map((subArr) => Math.max(...subArr));
console.log(
  findLargest([
    [4, 5, 1, 3],
    [13, 27, 18, 26],
    [32, 35, 37, 39],
    [1000, 1001, 857, 1],
  ])
); // [5, 27, 39, 1001]
Enter fullscreen mode Exit fullscreen mode

Find smallest numbers 



const findSmallest = (arr) => arr.map((subArr) => Math.min(...subArr));
console.log(
  findSmallest([
    [4, 5, 1, 3],
    [13, 27, 18, 26],
    [32, 35, 37, 39],
    [1000, 1001, 857, 1],
  ])
); // [1, 18, 32, 857]
Enter fullscreen mode Exit fullscreen mode

Pick a random element from an array 



const pick = (arr) => arr[Math.floor(Math.random() * arr.length)];
console.log(pick([1, 2, 3, 4])); // 2
Enter fullscreen mode Exit fullscreen mode

Convert array to object 



const toObject = (arr) => ({ ...arr });
console.log(toObject(["a", "b"])); // { 0: 'a', 1: 'b' }
Enter fullscreen mode Exit fullscreen mode

Find intersection of two arrays 



const intersection = (arr1, arr2) => {
  const set = new Set(arr1);
  return arr2.filter((x) => set.has(x));
};
console.log(intersection([1, 2, 3], [2, 3, 4])); // [2, 3]
Enter fullscreen mode Exit fullscreen mode

Remove falsy values from an array 



const compact = (arr) => arr.filter(Boolean);
console.log(compact([0, 1, false, 2, "", 3, "a", "e" * 23, NaN, "s", 34])); // [1, 2, 3, 'a', 's', 34]
Enter fullscreen mode Exit fullscreen mode

Reverse String 



const reverseString = (str) => str.split("").reverse().join("");
console.log(reverseString("hello")); // olleh
Enter fullscreen mode Exit fullscreen mode

Is String Palindrome 



const isPalindrome = (str) => str === str.split("").reverse().join("");
console.log(isPalindrome("madam")); // true
Enter fullscreen mode Exit fullscreen mode

Check object is empty or not 



const isEmpty = (obj) => Object.keys(obj).length === 0;
console.log(isEmpty({})); // true
Enter fullscreen mode Exit fullscreen mode

Find the number of days in a month 



const getDaysInMonth = (date) =>
  new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate();
console.log(getDaysInMonth(new Date())); // 31
Enter fullscreen mode Exit fullscreen mode

Generate a random color 



const getRandomColor = () =>
  `#${Math.floor(Math.random() * 16777215).toString(16)}`;
console.log(getRandomColor()); // #f0f0f0

const randomHex = () =>
  `#${Math.floor(Math.random() * 0xffffff)
    .toString(16)
    .padEnd(6, "0")}`;
console.log(randomHex()); // #f0f0f0
Enter fullscreen mode Exit fullscreen mode
Must Read If you haven't
devsmitra

How to create JSX template engine from scratch

Rahul Sharma ・ Nov 23 '22

#jsx #react #javascript #webdev
devsmitra

React.js state management using signals

Rahul Sharma ・ Sep 21 '22

#react #signals #preact #javascript
devsmitra

Simplify JavaScript's Async Concepts with One GIF

Rahul Sharma ・ Nov 2 '23

#javascript #async #webdev #beginners
More content at Dev.to.
devsmitra image

Rahul Sharma

Passionate JavaScript Developer 🚀 | Crafting Web Magic ✨ | Code Enthusiast 💻
Catch me on

Youtube Github LinkedIn Medium Stackblitz Hashnode HackerNoon

Top comments (10)

Collapse
 
tcjr profile image
Tom Carter •

Nice list, but that shuffle function is not good and should be avoided. You can read all about the problems here: robweir.com/blog/2010/02/microsoft...

Collapse
 
joseph42a profile image
Joseph42A •

Nice well done, just find a shorter way to build array from (n) numbers
Array.from(Array(n).keys())

Collapse
 
pierre profile image
Pierre-Henry Soria ✨ •

Nice list Rahul 🙂

Collapse
 
wemmersonalb profile image
Wemmerson Albuquerque •

Nice! It reminded me of coding marathons =D

Collapse
 
timot profile image
Timothy Joseph Eslabra •

this will help me a lot on learning JavaScript thank you so much Rahul <3

Collapse
 
mexikode profile image
MexiKode ⚙ • • Edited


var kkeys = [], konami = "38,38,40,40,37,39,37,39,66,65";
window.addEventListener("keydown", function(e){
kkeys.push( e.keyCode );
if ( kkeys.toString().indexOf( konami ) >= 0 )
kkeys = [];
}, true);

99 lives

Collapse
 
mexikode profile image
MexiKode ⚙ •

generate cache-busting parameter for assets
let v = Date.now();

find needle in any string, example in path
if(top.location.href.includes('/blog')) //is in blog post view

get name of uri hash
let section = top.location.hash.substr(1);

Collapse
 
tushar1471 profile image
TUSHAR MALHOTRA •

function shuffleArray(new_arr) {
for (let i = new_arr.length - 1; i >= 0; i--) {
const j = Math.floor(Math.random() * (i + 1));
[new_arr[i], new_arr[j]] = [new_arr[j], new_arr[i]];
}
return new_arr;

}

console.log(shuffleArray(new_arr)); For shuffling array

Collapse
 
ahsaniftikhar99 profile image
Ahsan Iftikhar •

Brother how did you made the code snippet looked colored?

Collapse
 
devsmitra profile image
Rahul Sharma •

Check this out:
github.com/darsaveli/Readme-Markdo...

dev.to/devteam/ways-to-enhance-you...

Some comments may only be visible to logged-in visitors. Sign in to view all comments.

Read next

iamdevmarcos profile image

React Hydration Explained 🔥

Marcos Mendes -

ronieremarques profile image

Roniere Marques: Um Desenvolvedor em Destaque

Roniere da silva marques -

sam45 profile image

looking forward to meeting senior frontend developers

samsandhu -

adeleyeayodeji profile image

How to Stop Spam Comments on WordPress WITHOUT Any Plugin

Adeleye Ayodeji -