JavaScript remains one of the most popular and versatile programming languages in the world, empowering developers to build dynamic and responsive web applications. Whether you’re a novice learning the ropes or a seasoned coder looking to refine your skills, mastering JavaScript can open new doors and opportunities. Here, we present a series of JavaScript code snippets that cover a variety of common programming tasks. Each snippet is a mini-lesson in itself, designed to enhance your coding skills and deepen your understanding of JavaScript fundamentals.
1. Determining Leap Years
Leap years are a quirky aspect of our calendar system, and determining whether a year is a leap year is a common task in programming. Here’s a function that checks if a given year is a leap year:
function isLeapYear(year) {
return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
}
console.log(isLeapYear(2020)); // Output: true
console.log(isLeapYear(1900)); // Output: false
2. Reversing Numbers in an Array
Sometimes, you might want to manipulate numbers for data formatting or game development logic. This function reverses each number in an array:
function reverseEachNumber(arr) {
return arr.map(num => parseInt(num.toString().split('').reverse().join('')));
}
console.log(reverseEachNumber([123, 456, 789])); // Output: [321, 654, 987]
3. Summing Even Numbers
Calculating the sum of even numbers up to a given number can be useful in various statistical computations:
function sumOfEvens(n) {
let sum = 0;
for (let i = 0; i <= n; i += 2) {
sum += i;
}
return sum;
}
console.log(sumOfEvens(10)); // Output: 30
4. Converting Arrays to Objects with Counts
This function is particularly useful for data analysis, helping to quickly count occurrences of items within an array:
function arrayToObjectWithCounts(arr) {
const counts = {};
arr.forEach(item => {
counts[item] = (counts[item] || 0) + 1;
});
return counts;
}
console.log(arrayToObjectWithCounts(['apple', 'banana', 'apple'])); // Output: { apple: 2, banana: 1 }
5. Checking for Unique Characters in a String
A handy snippet for password validation or cryptography-related tasks:
function areAllCharactersUnique(str) {
const seen = new Set();
for (let char of str) {
if (seen.has(char)) {
return false;
}
seen.add(char);
}
return true;
}
console.log(areAllCharactersUnique("abcdef")); // Output: true
console.log(areAllCharactersUnique("abacdefb")); // Output: false
Each of these snippets demonstrates fundamental JavaScript techniques that are applicable in real-world programming scenarios. From handling text and numbers to working with collections and performing conditional checks, these examples help cement your JavaScript knowledge through practical application.
Whether you’re working on a personal project, contributing to an open-source initiative, or developing professional software, these JavaScript snippets can help streamline your coding tasks and enhance your overall programming efficiency. Dive into each example, experiment with modifications, and see how you can integrate these into your projects!
///Check if Year is Leap Year
function isLeapYear(year) {
return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
}
console.log(isLeapYear(2020)); // Output: true
console.log(isLeapYear(1900)); // Output: false
///Reverse Each Number in an Array
function reverseEachNumber(arr) {
return arr.map(num => parseInt(num.toString().split('').reverse().join('')));
}
console.log(reverseEachNumber([123, 456, 789])); // Output: [321, 654, 987]
///Calculate the Sum of Even Numbers
function sumOfEvens(n) {
let sum = 0;
for (let i = 0; i <= n; i += 2) {
sum += i;
}
return sum;
}
console.log(sumOfEvens(10)); // Output: 30 (0+2+4+6+8+10)
///Convert Array to Object with Counter
function arrayToObjectWithCounts(arr) {
const counts = {};
arr.forEach(item => {
counts[item] = (counts[item] || 0) + 1;
});
return counts;
}
console.log(arrayToObjectWithCounts(['apple', 'banana', 'apple'])); // Output: { apple: 2, banana: 1 }
///Check If All Characters Are Unique in a String
function areAllCharactersUnique(str) {
const seen = new Set();
for (let char of str) {
if (seen.has(char)) {
return false;
}
seen.add(char);
}
return true;
}
console.log(areAllCharactersUnique("abcdef")); // Output: true
console.log(areAllCharactersUnique("abacdefb")); // Output: false
///Remove Specific Element from Array
function removeElement(arr, element) {
const result = [];
for (let i = 0; i < arr.length; i++) {
if (arr[i] !== element) {
result.push(arr[i]);
}
}
return result;
}
console.log(removeElement([1, 2, 3, 4, 3], 3)); // Output: [1, 2, 4]
///Determine the Longest String in an Array
function findLongestString(strings) {
return strings.reduce((longest, current) => current.length > longest.length ? current : longest, "");
}
console.log(findLongestString(["short", "medium", "longest", "longer"])); // Output: "longest"
///Generate a Random Hex Color
function generateRandomHexColor() {
return '#' + Math.floor(Math.random() * 0xffffff).toString(16).padStart(6, '0');
}
console.log(generateRandomHexColor()); // Output: e.g., "#1a2b3c"
///Extract Unique Characters from a String
function extractUniqueChars(str) {
const uniqueChars = new Set(str.split(''));
return [...uniqueChars].join('');
}
console.log(extractUniqueChars("hello world")); // Output: "helo wrd"
///Count True Values in an Array
function countTrue(arr) {
return arr.filter(Boolean).length;
}
console.log(countTrue([true, false, true, false, true])); // Output: 3
///Alternate Case in a String
function alternateCase(str) {
let result = '';
let lower = true;
for (let char of str) {
if (/[a-z]/i.test(char)) {
result += lower ? char.toLowerCase() : char.toUpperCase();
lower = !lower;
} else {
result += char;
}
}
return result;
}
console.log(alternateCase("hello world")); // Output: "hElLo wOrLd"
///Check if a Number is a Perfect Square
function isPerfectSquare(num) {
const squareRoot = Math.sqrt(num);
return squareRoot === Math.floor(squareRoot);
}
console.log(isPerfectSquare(16)); // Output: true
console.log(isPerfectSquare(14)); // Output: false
///Convert String to Title Case
function toTitleCase(str) {
return str.toLowerCase().split(' ').map(word => word.charAt(0).toUpperCase() + word.slice(1)).join(' ');
}
console.log(toTitleCase("hello world")); // Output: "Hello World"
///Check if Two Arrays Are Equal
function arraysEqual(arr1, arr2) {
if (arr1.length !== arr2.length) return false;
for (let i = 0; i < arr1.length; i++) {
if (arr1[i] !== arr2[i]) {
return false;
}
}
return true;
}
console.log(arraysEqual([1, 2, 3], [1, 2, 3])); // Output: true
console.log(arraysEqual([1, 2, 3], [3, 2, 1])); // Output: false
///Remove All Occurrences of a Specific Value from an Array
function removeAllOccurrences(arr, valueToRemove) {
return arr.filter(item => item !== valueToRemove);
}
console.log(removeAllOccurrences([1, 2, 3, 2, 4], 2)); // Output: [1, 3, 4]
///Generate an Array of Letters
function generateAlphabet() {
const alphabet = [];
for (let i = 0; i < 26; i++) {
alphabet.push(String.fromCharCode(97 + i));
}
return alphabet;
}
console.log(generateAlphabet()); // Output: ['a', 'b', 'c', ..., 'z']
///Sum All Even Numbers in an Array
function sumEvenNumbers(arr) {
return arr.reduce((sum, num) => num % 2 === 0 ? sum + num : sum, 0);
}
console.log(sumEvenNumbers([1, 2, 3, 4, 5, 6])); // Output: 12
///Find Maximum Difference in an Array
function maxDifference(arr) {
let minElement = arr[0];
let maxDiff = 0;
arr.forEach(num => {
if (num < minElement) {
minElement = num;
}
const difference = num - minElement;
if (difference > maxDiff) {
maxDiff = difference;
}
});
return maxDiff;
}
console.log(maxDifference([2, 3, 10, 6, 4])); // Output: 8
///Convert First Character of Each Word to Uppercase
function capitalizeFirstLetters(str) {
return str.replace(/\b[a-z]/g, char => char.toUpperCase());
}
///Count Occurrences of a Substring in a String
function countOccurrences(str, substring) {
const regex = new RegExp(substring, 'g');
return (str.match(regex) || []).length;
}
