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Front End Technology Articles
Page 195 of 652
Listing all the prime numbers upto a specific number in JavaScript
We are required to write a JavaScript function that takes in a number, say n, and returns an array containing all the prime numbers up to n. For example: If the number n is 24. Then the output should be − const output = [2, 3, 5, 7, 11, 13, 17, 19, 23]; Therefore, let's write the code for this function − Method 1: Using Helper Function for Prime Check This approach uses a helper function to check if a number is prime, then iterates through numbers up to n: ...
Read MoreSwitching positions of selected characters in a string in JavaScript
We are required to write a JavaScript function that takes in a string containing only the letters 'k', 'l' and 'm'. The task is to switch the positions of 'k' with 'l' while leaving all instances of 'm' at their original positions. Problem Statement Given a string with characters 'k', 'l', and 'm', we need to swap every occurrence of 'k' with 'l' and vice versa, keeping 'm' unchanged. Example Here's the implementation using a simple loop approach: const str = 'kklkmlkk'; const switchPositions = (str = '') => { ...
Read MoreFinding product of Number digits in JavaScript
We are required to write a JavaScript program that takes in a number and finds the product of all of its digits. Input Output Scenarios Here are examples of finding the product of number digits: Input = 12345 Output = 120 (1 × 2 × 3 × 4 × 5 = 120) We can also work with string numbers and convert them to integers: Input = "12345" Output = 120 Using Math.floor() and Modulo Operator The Math.floor() function returns the largest integer less than or equal to a given ...
Read MoreRemoving the second number of the pair that add up to a target in JavaScript
Problem We need to write a JavaScript function that takes an array of numbers and a target sum. The function should remove the second number from any consecutive pair of numbers that add up to the target. Example Let's see how this works with a practical example: const arr = [1, 2, 3, 4, 5]; const target = 3; const removeSecond = (arr = [], target = 1) => { const res = [arr[0]]; for(let i = 1; i < arr.length; i++){ ...
Read MoreIf the element repeats, remove all its instances from array in JavaScript
When working with arrays in JavaScript, sometimes you need to remove all instances of elements that appear more than once, keeping only elements that appear exactly once. This is different from typical deduplication where you keep one instance of each duplicate. For example, if the input is: const arr = [763, 55, 43, 22, 32, 43, 763, 43]; console.log("Original array:", arr); Original array: [ 763, 55, 43, 22, 32, 43, 763, 43 ] The output should be: [ 55, 22, 32 ] Notice that 763 and 43 are ...
Read MoreInterchanging first letters of words in a string in JavaScript
We need to write a JavaScript function that takes a string containing exactly two words and swaps their first letters to create a new string. Problem Statement Given a string with two words separated by a space, we want to interchange the first character of each word while keeping the rest of the characters in their original positions. Example For input "hello world", we should get "wello horld" where 'h' and 'w' are swapped. const str = 'hello world'; const interchangeChars = (str = '') => { const [first, second] ...
Read MoreArray flattening using loops and recursion in JavaScript
Array flattening converts nested arrays into a single-level array. JavaScript provides multiple approaches including loops, recursion, and built-in methods. Problem Overview Given a nested array with mixed data types including falsy values, we need to flatten it completely: const arr = [[1, 2, 3], [4, 5, [5, false, 6, [5, 8, null]]], [6]]; console.log("Input:", arr); Input: [ [ 1, 2, 3 ], [ 4, 5, [ 5, false, 6, [Array] ] ], [ 6 ] ] Expected output should be a flat array preserving all values including false and null: ...
Read MorePerforming power operations on an array of numbers in JavaScript
We need to write a JavaScript function that takes an array of integers with even length and performs a specific power operation to find two numbers whose squares sum to a calculated value. Problem Statement Given an array of integers with even length, we calculate: num = (arr[0]² + arr[1]²) × (arr[2]² + arr[3]²) × ... × (arr[n-2]² + arr[n-1]²) Our function should return an array [A, B] such that A² + B² = num. Example Walkthrough For array [1, 2, 3, 4]: First pair: 1² + 2² = 1 ...
Read MoreUsing recursion to remove consecutive duplicate entries from an array in JavaScript
We are supposed to write a function that takes in an array of number/string literals. The function should remove all the redundant consecutive elements of the array without using extra memory space. For example, if the input array is − const arr = [17, 17, 17, 12, 12, 354, 354, 1, 1, 1]; Then the output should be − const output = [17, 12, 354, 1]; Therefore, let's write the code for this function − How the Algorithm Works The recursive function works by checking each element against its ...
Read MoreFinding the product of array elements with reduce() in JavaScript
We are required to write a JavaScript function that takes in an array and finds the product of all its elements using the reduce() method. Understanding reduce() for Products The reduce() method executes a reducer function on each array element, accumulating results into a single value. For multiplication, we start with an initial value of 1 and multiply each element. Syntax array.reduce((accumulator, currentValue) => { return accumulator * currentValue; }, 1); Example: Basic Product Calculation const arr = [3, 1, 4, 1, 2, -2, -1]; const ...
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