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Front End Technology Articles
Page 443 of 652
Convert a string to hierarchical object - JavaScript
Let’s say, we have a special kind of string that contains characters in couple, like this −const str = "AABBCCDDEE";We are required to construct an object based on this string which should look like this −const obj = { code: "AA", sub: { code: "BB", sub: { code: "CC", sub: { code: "DD", sub: { code: "EE", ...
Read MoreRemove elements from array using JavaScript filter - JavaScript
Suppose, we have two arrays of literals like these −const arr1 = [4, 23, 7, 6, 3, 6, 4, 3, 56, 4]; const arr2 = [4, 56, 23];We are required to write a JavaScript function that takes in these two arrays and filters the first to contain only those elements that are not present in the second array.And then return the filtered array to get the below output −const output = [7, 6, 3, 6, 3];ExampleFollowing is the code −const arr1 = [4, 23, 7, 6, 3, 6, 4, 3, 56, 4]; const arr2 = [4, 56, 23]; const filterArray = (arr1, arr2) => { const filtered = arr1.filter(el => { return arr2.indexOf(el) === -1; }); return filtered; }; console.log(filterArray(arr1, arr2));OutputThis will produce the following output in console −[ 7, 6, 3, 6, 3 ]
Read MoreHow to merge an array with an object where values are arrays - JavaScript
Suppose, we have an array and an object like these −const arr = [1, 2, 3, 4, 5]; const obj = { group1: ["Ram", "Mohan", "Shyam"], group2: ["Jai", "Dinesh"], };We are required to zip the array and the object so that the values in the array are assigned to the new objects that are keyed with the values in the object.Like this −const output = { group1: { "Ram": 1, "Mohan": 2, "Shyam": 3 }, group2: { "Jai": 4, "Dinesh": ...
Read MoreRemoving identical entries from an array keeping its length same - 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.For example −If we find four duplicate values, we have to remove then all and insert four empty strings at the end.ExampleFollowing is the code −const arr = [1, 2, 3, 1, 2, 3, 2, 2, 3, 4, 5, 5, 12, 1, 23, 4, 1]; const deleteAndInsert = arr => { const creds = arr.reduce((acc, val, ind, array) => { let { count, res } = acc; ...
Read MoreFinding the maximum in a nested array - JavaScript
Let’s say, we have to write a simple function in JavaScript that takes in the following array of Numbers (nested to any level) −const arr = [ 15, 24, [ 29, 85, 56, [ 36, 14, 6, 98, 34, 52 ], 22 ], 87, 60 ];and return the greatest number present in the array.For example, If the input array is −const arr = [ 34, 65, 67, [ 43, 76, 87, 23, 56, 7, ...
Read MoreBuild maximum array based on a 2-D array - JavaScript
Let’s say, we have an array of arrays of Numbers like below −const arr = [ [1, 16, 34, 48], [6, 66, 2, 98], [43, 8, 65, 43], [32, 98, 76, 83], [65, 89, 32, 4], ];We are required to write a function that maps over this array of arrays and returns an array that contains the maximum (greatest) element from each subarray.So, for the above array, the output should be −const output = [ 48, 98, 65, 83, 89 ];ExampleFollowing is the code to get the greatest element from each subarray −const arr = [ [1, 16, 34, 48], [6, 66, 2, 98], [43, 8, 65, 43], [32, 98, 76, 83], [65, 89, 32, 4], ]; const constructBig = arr => { return arr.map(sub => { const max = Math.max(...sub); return max; }); }; console.log(constructBig(arr));OutputThis will produce the following output in console −[ 48, 98, 65, 98, 89 ]
Read MoreArray of adjacent element's average - JavaScript
Let’s say, we have an array of numbers −const arr = [3, 5, 7, 8, 3, 5, 7, 4, 2, 8, 4, 2, 1];We are required to write a function that returns an array with the average of the corresponding element and its predecessor. For the first element, as there are no predecessors, so that very element should be returned.Let’s write the code for this function, we will use the Array.prototype.map() function to solve this problem −Exampleconst arr = [3, 5, 7, 8, 3, 5, 7, 4, 2, 8, 4, 2, 1]; const consecutiveAverage = arr => { return ...
Read MoreInserting element at falsy index in an array - JavaScript
We are required to write an Array function, let’s say, pushAtFalsy() The function should take in an array and an element. It should insert the element at the first falsy index it finds in the array.If there are no empty spaces, the element should be inserted at the last of the array.We will first search for the index of empty position and then replace the value there with the value we are provided with.ExampleFollowing is the code −const arr = [13, 34, 65, null, 64, false, 65, 14, undefined, 0, , 5, , 6, ,85, ,334]; const pushAtFalsy = function(element){ ...
Read MoreAlternative shuffle in JavaScript
Alternative ShuffleAn alternatively shuffled array in JavaScript is an array of Numbers in which numbers are indexed such that greatest number is followed by the smallest element, second greatest element is followed by second smallest element and so on.For example: If the input array is −const arr = [11, 7, 9, 3, 5, 1, 13];Then the output should be &minusconst output = [13, 1, 11, 3, 9, 5, 7];ExampleFollowing is the code −const arr = [11, 7, 9, 3, 5, 1, 13]; const sorter = (a, b) => a - b; const alternateShuffle = (arr) => { const array ...
Read MoreUsing recursion to remove consecutive duplicate entries from an array - 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];ExampleFollowing is the code −const arr = [17, 17, 17, 12, 12, 354, 354, 1, 1, 1]; const comp = (arr, len = 0, deletable = false) => { if(len < arr.length){ if(deletable){ arr.splice(len, 1); len--; } return comp(arr, len+1, arr[len] === arr[len+1]) }; return; }; comp(arr); console.log(arr);OutputThis will produce the following output in console −[ 17, 12, 354, 1 ]
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