1. Generating a Random Number
let randomNum = Math.floor(Math.random() * maxNum);
2. Checking If an Object is Empty
function isEmptyObject(obj) {
return Object.keys(obj).length === 0;
}
3. Creating a Countdown Timer
function countdownTimer(minutes) {
let seconds = minutes * 60;
let interval = setInterval(() => {
if (seconds <= 0) {
clearInterval(interval);
console.log("Time's up!");
} else {
console.log(`${Math.floor(seconds / 60)}:${seconds % 60}`);
seconds--;
}
}, 1000);
}
4. Sorting an Array of Objects
function sortByProperty(arr, property) {
return arr.sort((a, b) => (a[property] > b[property]) ? 1 : -1);
}
5. Removing Duplicates from an Array
let uniqueArr = [...new Set(arr)];
6. Truncating a String
function truncateString(str, num) {
return str.length > num ? str.slice(0, num) + "..." : str;
}
7. Converting a String to Title Case
function toTitleCase(str) {
return str.replace(/\b\w/g, txt => txt.toUpperCase());
}
8. Checking If a Value Exists in an Array
let isValueInArray = arr.includes(value);
9. Reversing a String
let reversedStr = str.split("").reverse().join("");
10. Creating a New Array from an Existing Array
let newArr = oldArr.map(item => item + 1);
11. Debouncing Function Calls
function debounce(func, delay) {
let timeout;
return function(...args) {
clearTimeout(timeout);
timeout = setTimeout(() => func.apply(this, args), delay);
};
}
12. Throttling Function Calls
function throttle(func, limit) {
let lastFunc;
let lastRan;
return function(...args) {
if (!lastRan) {
func.apply(this, args);
lastRan = Date.now();
} else {
clearTimeout(lastFunc);
lastFunc = setTimeout(function() {
if ((Date.now() - lastRan) >= limit) {
func.apply(this, args);
lastRan = Date.now();
}
}, limit - (Date.now() - lastRan));
}
};
}
13. Cloning an Object
const cloneObject = (obj) => ({ ...obj });
14. Merging Two Objects
const mergeObjects = (obj1, obj2) => ({ ...obj1, ...obj2 });
15. Checking for Palindrome Strings
function isPalindrome(str) {
const cleanedStr = str.replace(/[^A-Za-z0-9]/g, '').toLowerCase();
return cleanedStr === cleanedStr.split('').reverse().join('');
}
16. Counting Occurrences in an Array
const countOccurrences = (arr) =>
arr.reduce((acc, val) => (acc[val] ? acc[val]++ : acc[val] = 1, acc), {});
17. Getting the Day of the Year from a Date Object
const dayOfYear = date =>
Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);
18. Filtering Unique Values from an Array
const uniqueValues = arr => [...new Set(arr)];
19. Converting Degrees to Radians
const degreesToRads = deg => (deg * Math.PI) / 180;
20. Delaying Function Execution
const defer = (fn, ...args) => setTimeout(fn, 1, ...args);
21. Flattening a Nested Array
const flattenArray = arr => arr.flat(Infinity);
22. Getting a Random Item from an Array
const randomItem = arr => arr[Math.floor(Math.random() * arr.length)];
23. Capitalizing the First Letter of a String
const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1);
24. Finding the Max Value in an Array
const maxVal = arr => Math.max(...arr);
25. Finding the Min Value in an Array
const minVal = arr => Math.min(...arr);
26. Shuffling an Array
function shuffleArray(arr) {
return arr.sort(() => Math.random() - 0.5);
}
27. Removing Falsy Values from an Array
const removeFalsy = arr => arr.filter(Boolean);
28. Generating a Range of Numbers
const range = (start, end) => Array.from({ length: end - start + 1 }, (_, i) => i + start);
29. Checking if Two Arrays are Equal
const arraysEqual = (a, b) =>
a.length === b.length && a.every((val, i) => val === b[i]);
30. Checking if a Number is Even
const isEven = num => num % 2 === 0;
31. Checking if a Number is Odd
const isOdd = num => num % 2 !== 0;
32. Removing Whitespace from a String
const removeSpaces = str => str.replace(/\s+/g, '');
33. Checking If a String is JSON
function isJSON(str) {
try {
JSON.parse(str);
return true;
} catch {
return false;
}
}
34. Deep Cloning an Object
const deepClone = obj => JSON.parse(JSON.stringify(obj));
35. Checking if a Number is Prime
function isPrime(num) {
if (num <= 1) return false;
for (let i = 2; i <= Math.sqrt(num); i++) {
if (num % i === 0) return false;
}
return true;
}
36. Finding Factorial of a Number
const factorial = num =>
num <= 1 ? 1 : num * factorial(num - 1);
37. Getting Current Timestamp
const timestamp = Date.now();
38. Formatting Date as YYYY-MM-DD
const formatDate = date => date.toISOString().split('T')[0];
39. Generating UUID (Simple)
const uuid = () =>
'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
const r = Math.random() * 16 | 0;
const v = c === 'x' ? r : (r & 0x3 | 0x8);
return v.toString(16);
});
40. Checking if an Object has a Property
const hasProp = (obj, key) => key in obj;
41. Getting Query Parameters from URL
const getQueryParams = url =>
Object.fromEntries(new URLSearchParams(new URL(url).search));
42. Escaping HTML Special Characters
const escapeHTML = str =>
str.replace(/[&<>'"]/g, tag => ({
'&':'&','<':'<','>':'>',
"'":''', '"':'"'
}[tag]));
43. Unescaping HTML Special Characters
const unescapeHTML = str =>
str.replace(/&(amp|lt|gt|#39|quot);/g, match => ({
'&':'&','<':'<','>':'>',
''':"'", '"':'"'
}[match]));
44. Sleep Function using Promise
const sleep = ms => new Promise(res => setTimeout(res, ms));
45. Sum of Array Elements
const sumArray = arr => arr.reduce((a, b) => a + b, 0);
46. Average of Numbers in Array
const avgArray = arr => arr.reduce((a, b) => a + b, 0) / arr.length;
47. Finding Intersection of Two Arrays
const intersection = (arr1, arr2) => arr1.filter(x => arr2.includes(x));
48. Finding Difference of Two Arrays
const difference = (arr1, arr2) => arr1.filter(x => !arr2.includes(x));
49. Checking if All Elements are Equal
const allEqual = arr => arr.every(val => val === arr[0]);
50. Generating a Random Hex Color
const randomHexColor = () =>
'#' + Math.floor(Math.random()*16777215).toString(16);