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Javascript Articles
Page 310 of 534
Add matching object values in JavaScript
Suppose, we have an array of objects like this −const arr = [{a: 2, b: 5, c: 6}, {a:3, b: 4, d:1}, {a: 1, d: 2}];Each object is bound to have unique in itself (for it to be a valid object), but two different objects can have the common keys (for the purpose of this question).We are required to write a JavaScript function that takes in one such array and returns an object with all the unique keys present in the array and their values cumulative sum as the value.So, the resultant object should look like −const output = {a: ...
Read MoreSorting a JSON object in JavaScript
Suppose we have an object like this −const obj = { key1: 56, key2: 67, key3: 23, key4: 11, key5: 88 };We are required to write a JavaScript function that takes in this object and returns a sorted array like this −const arr = [11, 23, 56, 67, 88];Here, we sorted the object values and placed them in an array.Therefore, let’s write the code for this function −ExampleThe code for this will be −const obj = { key1: 56, key2: 67, key3: 23, key4: 11, key5: 88 }; const sortObject ...
Read MoreFiltering array to contain palindrome elements in JavaScript
We are required to write a JavaScript function that takes in an array of String / Number literals and returns a subarray of all the elements that were palindrome in the original array.For exampleIf the input array is −const arr = ['carecar', 1344, 12321, 'did', 'cannot'];Then the output should be −const output = [12321, 'did'];We will create a helper function that takes in a number or a string and checks if its a boolean or not.Then we will loop over the array, filter the palindrome elements and return the filtered array.Therefore, let’s write the code for this function −ExampleThe code ...
Read MoreReverse mapping an object in JavaScript
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 are required to write a function that accepts a value and returns its key. Let' say we have created a function findKey().For example, findKey(110) should return "Apple".We will approach this problem by first reverse mapping the values to keys and then simply using object notations to find their values.Therefore, let’s write the code for this function −ExampleThe code for this will be −const products = { "Pineapple":38, ...
Read MoreExpanding Numerals in JavaScript
We are required to write a function that, given a number, say, 123, will output an array −[100, 20, 3]Basically, the function is expected to return an array that contains the place value of all the digits present in the number taken as an argument by the function.We can solve this problem by using a recursive approach.Therefore, let’s write the code for this function −ExampleThe code for this will be −const num = 123; const placeValue = (num, res = [], factor = 1) => { if(num){ const val = (num % 10) * factor; ...
Read MoreGrouping array of array on the basis of elements in JavaScript
Suppose, we have an array of arrays of numbers like this −const arr = [[1, 45], [1, 34], [1, 49], [2, 34], [4, 78], [2, 67], [4, 65]];Each subarray is bound to contain strictly two elements. We are required to write a function that constructs a new array where all second elements of the subarrays that have similar first value are grouped together.So, for the array above, the output should look like −const output = [ [45, 34, 49], [34, 67], [78, 65] ];We can make use of the Array.prototype.reduce() method that takes help of a Map() ...
Read MoreConstructing a nested JSON object in JavaScript
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", sub: {} ...
Read MoreRemoving 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.For example:If we find 4 duplicate values we have to remove then all and insert four empty strings at the end.Therefore, let’s write the code for this function −ExampleThe code for this will be −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 ...
Read MoreGreatest element in a Multi-Dimensional Array in JavaScript
We have to write a simple function in JavaScript that takes in an array of Numbers (nested to any level) 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, [ 54, 7, 87, 23, 79, 994, 2 ], 54 ], 54, 4, 2 ];Then the output should be −994We will use recursion to find the greatest number in the array, Therefore, let’s ...
Read MoreCumulative average of pair of elements in JavaScript
We have an array of numbers and 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.ExampleThe code for this will be −const arr = [3, 5, 7, 8, 3, 5, 7, 4, 2, 8, 4, 2, 1]; const consecutiveAverage = arr => { return arr.map((el, ind, array) => { const first = (array[ind-1] || ...
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