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Object Oriented Programming Articles
Page 31 of 589
Removing duplicates and inserting empty strings in JavaScript
We have to write a function that takes in an array, removes all duplicates from it and inserts the same number of empty strings at the end. Problem Description If we find 4 duplicate values we have to remove them all and insert four empty strings at the end. This maintains the original array length while eliminating duplicates. How It Works The algorithm uses reduce() to iterate through the array. For each element, it checks if the current index matches the last occurrence using lastIndexOf(). If yes, it's the final occurrence and gets added to the ...
Read MoreConstructing a nested JSON object in JavaScript
In JavaScript, we often need to construct nested objects from structured data. This article demonstrates how to build a nested JSON object from a string containing paired characters. Problem Statement Given a string with characters in pairs, we need to construct a nested object where each pair becomes a code property, and each level has a sub-object for the next pair. Input string: const str = "AABBCCDDEE"; Expected output structure: const obj = { code: "AA", sub: { ...
Read MoreGrouping array of array on the basis of elements in JavaScript
When working with arrays of arrays in JavaScript, you might need to group elements based on specific criteria. This article demonstrates how to group the second elements of subarrays that share the same first element. Problem Statement Suppose we have an array of arrays where each subarray contains exactly two elements: const arr = [[1, 45], [1, 34], [1, 49], [2, 34], [4, 78], [2, 67], [4, 65]]; console.log("Input array:", arr); Input array: [ [ 1, 45 ], [ 1, 34 ], [ 1, 49 ], [ 2, 34 ], [ 4, 78 ...
Read MoreReverse mapping an object in JavaScript
Reverse mapping an object in JavaScript involves swapping the keys and values of an object. This technique is useful when you need to look up keys based on their values. Suppose we have an object like this: const products = { "Pineapple": 38, "Apple": 110, "Pear": 109 }; All the keys are unique in themselves and all the values are unique in themselves. We need to write a function that accepts a value and returns its corresponding key. Method 1: Using Object.keys() with map() ...
Read MoreAdd matching object values in JavaScript
In JavaScript, you can add matching object values by iterating through an array of objects and accumulating values for common keys. This is useful for aggregating data from multiple objects. Consider an array of objects like this: const arr = [{a: 2, b: 5, c: 6}, {a: 3, b: 4, d: 1}, {a: 1, d: 2}]; console.log("Input array:", arr); Input array: [ { a: 2, b: 5, c: 6 }, { a: 3, b: 4, d: 1 }, { a: 1, d: 2 } ] Each object has unique properties within itself, ...
Read MoreSumming up unique array values in JavaScript
We are required to write a JavaScript function that takes in an array of numbers that may contain some duplicate numbers. Our function should return the sum of all the unique elements (elements that only appear once in the array) present in the array. Problem Understanding If the input array is: const arr = [2, 5, 5, 3, 2, 7, 4, 9, 9, 11]; The unique elements (appearing only once) are: 3, 7, 4, 11. Their sum is 3 + 7 + 4 + 11 = 25. Using indexOf() and lastIndexOf() We ...
Read MoreAbsolute difference of Number arrays in JavaScript
In JavaScript, calculating the absolute difference between corresponding elements of two arrays is a common operation. This involves subtracting elements at the same index positions and taking the absolute value of the result. Suppose we have two arrays like these: const arr1 = [1, 2, 3, 4, 5, 6]; const arr2 = [9, 8, 7, 5, 8, 3]; We need to create a function that returns an array of absolute differences between corresponding elements. For these arrays, the expected output should be: [8, 6, 4, 1, 3, 3] Using For Loop ...
Read MoreSort the second array according to the elements of the first array in JavaScript
Suppose, we have two arrays like these − const arr1 = ['d', 'a', 'b', 'c']; const arr2 = [{a:1}, {c:3}, {d:4}, {b:2}]; console.log("First array:", arr1); console.log("Second array:", arr2); First array: [ 'd', 'a', 'b', 'c' ] Second array: [ { a: 1 }, { c: 3 }, { d: 4 }, { b: 2 } ] We are required to write a JavaScript function that accepts these two arrays. The function should sort the second array according to the elements of the first array. We have to sort the keys of ...
Read MorePushing false objects to bottom in JavaScript
Suppose we have an array of objects like this − const array = [ {key: 'a', value: false}, {key: 'a', value: 100}, {key: 'a', value: null}, {key: 'a', value: 23} ]; We are required to write a JavaScript function that takes in one such array and places all the objects that have falsy values for the "value" property to the bottom and sorts all other objects in decreasing order by the "value" property. Understanding Falsy Values In JavaScript, falsy values include: false, ...
Read MoreNon-composite numbers sum in an array in JavaScript
In JavaScript, you can calculate the sum of all prime numbers in an array by first checking each number for primality, then adding the prime numbers together. A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Understanding Prime Numbers Prime numbers are numbers like 2, 3, 5, 7, 11, 13, etc. The number 1 is not considered prime, and 2 is the only even prime number. Creating a Prime Check Function First, we need a helper function to determine if a number is prime: ...
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