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Javascript Articles
Page 66 of 534
Retaining array elements greater than cumulative sum using reduce() in JavaScript
We need to write a JavaScript function that takes an array of numbers and returns a new array containing only elements that are greater than the cumulative sum of all previous elements. We'll solve this using the Array.prototype.reduce() method. Problem Understanding For each element in the array, we compare it with the sum of all elements that came before it. If the current element is greater than this cumulative sum, we include it in the result array. Example Let's implement the solution using reduce(): const arr = [1, 2, 30, 4, 5, 6]; ...
Read MoreRemoving duplicate values in a twodimensional array in JavaScript
When working with two-dimensional arrays in JavaScript, you may need to remove duplicate values that appear across different sub-arrays. This article shows how to create a function that removes all duplicate values from a 2D array, keeping only the first occurrence of each value. Problem Statement We need to write a JavaScript function that takes a two-dimensional array and returns a new array where duplicate values across all sub-arrays are removed, preserving only the first occurrence of each value. Example Here's how to implement this functionality: const arr = [ ...
Read MoreString replace multiple characters with an asterisk in JavaScript
We are required to write a JavaScript function that takes in a string as the first argument and an array of numbers. Our function should replace all the characters in the string at indices that are specified by the array elements taken as the second argument with an asterisk. Example The code for this will be − const str = "Lorem ipsum dolor sit amet consectetur adipiscing elit"; const arr = [4, 7, 9, 12, 15]; const replaceWithAsterisk = (str, indices) => { let res = ''; res ...
Read MoreGrouping and sorting 2-D array in JavaScript
Suppose we have a two-dimensional array of numbers like this − const arr = [ [1, 3, 2], [5, 2, 1, 4], [2, 1] ]; We are required to write a JavaScript function that groups all the identical numbers into their own separate subarray, and then the function should sort the group array to place the subarrays into increasing order. Therefore, finally the new array should look like − const output = [ [1, 1, 1], [2, 2, ...
Read MoreHow to sort array according to age in JavaScript?
We are required to write a JavaScript function that takes in an array of numbers representing ages of some people. Then the function should bring all the ages less than 18 to the front of the array without using any extra memory. Understanding the Problem We need to sort an array so that all minors (ages < 18) appear before adults (ages ≥ 18), while maintaining the original order within each group. Example The code for this will be − const ages = [23, 56, 56, 3, 67, 8, 4, 34, 23, 12, ...
Read MorePadding a string with random lowercase alphabets to fill length in JavaScript
We are required to write a function that takes in two arguments, first is a string and second is a number. The length of string is always less than or equal to the number. We have to insert some random lowercase alphabets at the end of the string so that its length becomes exactly equal to the number and we have to return the new string. Example Let's write the code for this function — const padString = (str, len) => { if(str.length < len){ ...
Read MoreJavaScript Array: Checking for multiple values
We are required to write a JavaScript function that takes in two arrays of Numbers and checks whether all the elements of the first array exist in the second or not. Example The code for this will be — const arr1 = [34, 78, 89]; const arr2 = [78, 67, 34, 99, 56, 89]; const multipleIncludes = (first, second) => { const indexArray = first.map(el => { return second.indexOf(el); }); return indexArray.indexOf(-1) === -1; } console.log(multipleIncludes(arr1, ...
Read MoreConsecutive elements sum array in JavaScript
We are required to write a JavaScript function that takes in an array of Numbers and returns a new array with elements as the sum of two consecutive elements from the original array. For example, if the input array is − const arr1 = [1, 1, 2, 7, 4, 5, 6, 7, 8, 9]; Then the output should be − const output = [2, 9, 9, 13, 17] How It Works The function pairs consecutive elements: (1+1=2), (2+7=9), (4+5=9), (6+7=13), (8+9=17). If the array has an odd length, the last ...
Read MoreFinding clusters of consecutive negative integers in JavaScript
We have an array of numbers like this: const arr = [-1, -2, -1, 0, -1, -2, -1, -2, -1, 0, 1, 0]; We are required to write a JavaScript function that counts the consecutive groups of negative numbers in the array. Understanding the Problem In the example array [-1, -2, -1, 0, -1, -2, -1, -2, -1, 0, 1, 0], we have: First cluster: [-1, -2, -1] (positions 0-2) Second cluster: [-1, -2, -1, -2, -1] (positions 4-8) The function should return 2 since there are two separate groups of ...
Read MoreDifference of digits at alternate indices in JavaScript
In JavaScript, we can calculate the difference between the sum of digits at even indices and the sum of digits at odd indices. This is useful for various mathematical operations and data validation scenarios. Problem Statement We need to write a JavaScript function that takes a number and returns the absolute difference between the sum of digits at even positions and the sum of digits at odd positions (counting from right to left, starting at index 0). Example For the number 123456: Even indices (0, 2, 4): digits 6, 4, 2 → sum = 12 ...
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