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Javascript Articles
Page 296 of 534
Finding sum of a range in an array JavaScript
We are required to write an Array function (functions that lives on Array.prototype object). The function should take in a start index and an end index and it should sum all the elements from start index to end index in the array (including both start and end)Exampleconst arr = [1, 2, 3, 4, 5, 6, 7]; const sumRange = function(start = 0, end = 1){ const res = []; if(start > end){ return res; }; for(let i = start; i
Read MoreDynamic Programming: Is second string subsequence of first JavaScript
We are given two strings str1 and str2, we are required to write a function that checks if str1 is a subsequence of str2.A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters.For example, "ace" is a subsequence of "abcde" while "aec" is notExampleconst str1 = 'ace'; const str2 = 'abcde'; const isSubsequence = (str1, str2) => { let i=0; let j=0; while(i
Read MoreSort array according to the date property of the objects JavaScript
We are required to write a JavaScript function that takes in an array of objects of dates like this −const arr = [ {date: "2016-06-08 18:10:00"}, {date: "2016-04-26 20:01:00"}, {date: "2017-02-06 14:38:00"}, {date: "2017-01-18 17:30:21"}, {date: "2017-01-18 17:24:00"} ];We are required to write a JavaScript function that takes in one such array. The function should then sort the array according to the date property of the objects.Exampleconst arr = [ {date: "2016-06-08 18:10:00"}, {date: "2016-04-26 20:01:00"}, {date: "2017-02-06 14:38:00"}, {date: "2017-01-18 17:30:21"}, {date: "2017-01-18 17:24:00"} ]; const sortByTime = (arr ...
Read MoreMerge JSON array date based JavaScript
Suppose, we have the following array of objects −const arr = [ { "date" : "2010-01-01", "price" : 30 }, { "date" : "2010-02-01", "price" : 40 }, { "date" : "2010-03-01", "price" : 50 }, { "date" : "2010-01-01", "price2" : 45 }, { "date" : "2010-05-01", "price2" : 40 }, { "date" : "2010-10-01", ...
Read MoreMerge JavaScript objects with the same key value and count them
Suppose, we have an array of objects like this −const arr = [{ "value": 10, "id": "111", "name": "BlackCat", }, { "value": 10, "id": "111", "name": "BlackCat", }, { "value": 15, "id": "777", "name": "WhiteCat", }];We are required to write a JavaScript function that takes in one such array.The function should then merge all those objects together that have the common value for "id" property.Therefore, for the above array, the output should look like −const output = [{ "value": 10, "id": "111", "name": "BlackCat", "count": 2, ...
Read MoreIs the second string a rotated version of the first string JavaScript
We are required to write a JavaScript function that takes in two strings, say str1 and str2. We are required to determine whether or not the second string is a rotated version of the first string.For example− If the input strings are −const str1 = 'abcde'; const str2 = 'cdeab';Then the output should be true because str2 is indeed made by shifting 'ab' to the end of string in str1.Exampleconst str1 = 'abcde'; const str2 = 'cdeab'; const isRotated = (str1, str2) => { if(str1.length !== str2.length){ return false }; if( (str1.length || str2.length) ...
Read MoreImplementing binary search in JavaScript to return the index if the searched number exist
We are required to write a JavaScript function that takes in a sorted array of numbers as the first argument and a search number as the second argument.If the search number exists in the array, we need to return its index in the array, otherwise we need to return -1.We have to do this making use of the binary search algorithm. The binary search algorithm is basically a divide and conquer algorithm which recursive divides the array into halves until it converses to a singleton element.The sorting of array is necessary of binary search algorithm in this case, as it ...
Read MoreIs uppercase used correctly JavaScript
For the purpose of this very problem, we define the correct use of uppercase letter by the following rules −All letters in a word are capitals, like "INDIA".All letters in a word are not capitals, like "example".Only the first letter in a word is capital, like "Ramesh".We are required to write a JavaScript function that takes in a string determines whether or not the string complies with any of these three rules.If it does then we return true, false otherwise.Exampleconst detectCapitalUse = (word = '') => { let allCap = true; for (let i = 0; i < ...
Read MoreGo through an array and sum only numbers JavaScript
We are required to write a JavaScript function that takes in an array. The array might contain any type of value, Number literals, string literals, objects, undefined.Our function should pick all the Number type values and return their sumExampleconst arr = [1, 2, 'a', 4]; const countNumbers = (arr = []) => { let sum = 0; for(let i = 0; i < arr.length; i++){ const el = arr[i]; if(+el){ sum += +el; }; }; return sum; } console.log(countNumbers(arr));OutputAnd the output in the console will be −7
Read MoreSort in multi-dimensional arrays in JavaScript
Suppose, we have the following array of arrays −const arr = [ ["A", "F", "A", "H", "F", "F"], ["F", "A", "A", "F", "F", "H"] ];We are required to write a JavaScript function that takes in one such array.The function should sort all the subarrays of the given array internally according to these rules −If the elements are not either "A" or "F", they should maintain their positionIf the element is either of "A" or "F", they should be sorted alphabeticallyTherefore, the final output for the above array should look like −const output = [ ["A", "A", "A", "H", "A", "F"], ...
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