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Articles on Trending Technologies
Technical articles with clear explanations and examples
Merge two objects in JavaScript ignoring undefined values
Suppose, we have two objects, say A and B like these −const A = { activity: 'purchased', count: undefined, time: '09:05:33' }; const B = { activity: 'purchased', count: '51', time: undefined }; We are required to write a JavaScript function that merges these two objects, keeping in mind if any key has a truthy value then it should not be overwritten by a key having falsy value.If we do this simply by using the spread operator, it will not keep track of truth or falsy values.Therefore, we have to do this using an iterative approach.ExampleFollowing is the code −const A ...
Read MoreSort an array to have specific items first in the array - JavaScript
Suppose, we have an array of objects like this −const arr = [ {flag: true, other: 1}, {flag: true, other: 2}, {flag: false, other: 3}, {flag: true, other: 4}, {flag: true, other: 5}, {flag: true, other: 6}, {flag: false, other: 7} ];We are required to write a JavaScript function that takes in one such array and sorts it based on the following conditions −If arr.flag === false, the matching element gets placed first in the array, but only after the previous matching elements.The elements that do not match, remain in the same order ...
Read MoreSort array of objects by string property value - JavaScript
Suppose, we have an array of Objects like this −const arr = [ { first_name: 'Lazslo', last_name: 'Jamf' }, { first_name: 'Pig', last_name: 'Bodine' }, { first_name: 'Pirate', last_name: 'Prentice' } ];We are required to write a JavaScript function that takes in one such array and sort this array according to the alphabetical value of the last_name key.ExampleFollowing is the code −const arr = [ { first_name: 'Lazslo', last_name: 'Jamf' }, { first_name: 'Pig', last_name: 'Bodine' }, { first_name: 'Pirate', last_name: 'Prentice' } ]; const sortByLastName = arr => { ...
Read MoreGrouping array nested value while comparing 2 objects - JavaScript
Suppose, we have the following JSON object −const input = { "before": { "device": [ { "id": "1234", "price": "10", "features": [ { "name": "samsung", "price": "10" }, { "name": "Apple", "price": "20" } ...
Read MoreCompare and fill arrays - JavaScript
We are required to write a function that compares two arrays and creates a third array filling that array with all the elements of the second array and filling null for all those elements that are present in the first array but misses out in the second array.For example −If the two arrays are −const arr1 = ['f', 'g', 'h']; const arr2 = ['f', 'h'];Then the output should be −const output = ['f', null, 'h'];ExampleFollowing is the code −const arr1 = ['f', 'g', 'h']; const arr2 = ['f', 'h']; const compareAndFill = (arr1, arr2) => { let offset = ...
Read MoreHow to validate if an element in an array is repeated? - JavaScript
We are required to write a JavaScript function that takes in two arguments −An Array, say arr, of literals that may contain some repeating elements.A number, say limit.The function should validate that no element of the array is repeated more than limit number of times. If any element is repeated more than the limit the function should return false, true otherwise.ExampleFollowing is the code −const arr = [4, 6, 7, 4, 2, 5, 7, 7, 4, 4, 3]; const validateElements = (arr, n) => { const counts = arr.reduce((acc, el) => { acc[el] = (acc[el] + ...
Read MoreCalculate Subtraction of diagonals-summations in a two-dimensional matrix using JavaScript
Suppose, we have a square matrix represented by a 2-D array in JavaScript like this −const arr = [ [1, 3, 5], [3, 5, 7], [2, 4, 2] ];We are required to write a JavaScript function that takes in one such array.The function should return the difference between the sum of elements present at the diagonals of the matrix.Like for the above matrix, the calculations will be −|(1+5+2) - (5+5+2)| |8 - 12| 4ExampleFollowing is the code −const arr = [ [1, 3, 5], [3, 5, 7], [2, 4, 2] ]; const diagonalDiff = ...
Read MoreFind closest index of array in JavaScript
Suppose, we have an array like this −const arr = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362];We are required to write a JavaScript function that takes in one such array and a number, say n.The function should return the index of item from the array which is closest to the number n.ExampleFollowing is the code −const arr = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362]; const closestIndex = (num, arr) => { let curr = arr[0], diff = Math.abs(num - curr); let index = 0; for (let val = 0; val ...
Read MoreRepeat even number inside the same array - JavaScript
We are required to write a JavaScript function that should repeat the even number inside the same array.Therefore, for example given the following array −const arr = [1, 2, 5, 6, 8];We should get the output −const output = [1, 2, 2, 5, 6, 6, 8, 8];ExampleFollowing is the code −const arr = [1, 2, 5, 6, 8]; const repeatEvenNumbers = arr => { let end = arr.length -1; for(let i = end; i > 0; i--){ if(arr[i] % 2 === 0){ arr.splice(i, 0, arr[i]); }; }; return arr; }; console.log(repeatEvenNumbers(arr));OutputThis will produce the following output on console −[ 1, 2, 2, 5, 6, 6, 8, 8 ]
Read MoreRecursion problem Snail Trail in JavaScript
Suppose, we have an array like this −const arr = [ [1, 2, 3, 4], [12, 13, 14, 5], [11, 16, 15, 6], [10, 9, 8, 7] ];The array is bound to be a square matrix.We are required to write a JavaScript function that takes in this array and constructs a new array by taking elements and spiraling in until it converges to center. A snail trail spiraling around the outside of the matrix and inwards.Therefore, the output for the above array should be −const output = [1, 2, 3, 4, 5, 6, 7, 8, 9, ...
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