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Front End Technology Articles
Page 324 of 652
Evaluating a mathematical expression considering Operator Precedence in JavaScript
ProblemWe are required to write a JavaScript function that takes in a mathematical expression as a string and return its result as a number.We need to support the following mathematical operators −Division / (as floating-point division)Addition +Subtraction -Multiplication *Operators are always evaluated from left-to-right, and * and / must be evaluated before + and -.ExampleFollowing is the code − Live Democonst exp = '6 - 4'; const findResult = (exp = '') => { const digits = '0123456789.'; const operators = ['+', '-', '*', '/', 'negate']; const legend = { '+': { pred: 2, func: ...
Read MoreSorting 2-D array of strings and finding the diagonal element using JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of n strings. And each string in the array consists of exactly n characters.Our function should first sort the array in alphabetical order. And then return the string formed by the characters present at the principal diagonal starting from the top left corner.ExampleFollowing is the code − Live Democonst arr = [ 'star', 'abcd', 'calm', 'need' ]; const sortPickDiagonal = () => { const copy = arr.slice(); copy.sort(); let res = ''; for(let i = 0; i < copy.length; i++){ ...
Read MoreFinding the sum of all common elements within arrays using JavaScript
ProblemWe are required to write a JavaScript function that takes in three arrays of numbers. Our function should return the sum of all those numbers that are common in all three arrays.ExampleFollowing is the code − Live Democonst arr1 = [4, 4, 5, 8, 3]; const arr2 = [7, 3, 7, 4, 1]; const arr3 = [11, 0, 7, 3, 4]; const sumCommon = (arr1 = [], arr2 = [], arr3 = []) => { let sum = 0; for(let i = 0; i < arr1.length; i++){ const el = arr1[i]; const ind2 = arr2.indexOf(el); const ind3 = arr3.indexOf(el); if(ind2 !== -1 && ind3 !== -1){ arr2.splice(ind2, 1); arr3.splice(ind3, 1); sum += el; }; }; return sum; }; console.log(sumCommon(arr1, arr2, arr3));Output7
Read MoreGreatest number divisible by n within a bound in JavaScript
ProblemWe are required to write a JavaScript function that takes in a number n and bound number b.Our function should find the largest integer num, such that −num is divisible by divisornum is less than or equal to boundnum is greater than 0.ExampleFollowing is the code − Live Democonst n = 14; const b = 400; const biggestDivisible = (n, b) => { let max = 0; for(let j = n; j max){ max = j; }; } return max; }; console.log(biggestDivisible(n, b));Output392
Read MoreFinding the sum of minimum value in each row of a 2-D array using JavaScript
ProblemWe are required to write a JavaScript function that takes in a 2-D array of numbers. Our function should pick the smallest number from each row of the 2-D array and then finally return the sum of those smallest numbers.ExampleFollowing is the code − Live Democonst arr = [ [2, 5, 1, 6], [6, 8, 5, 8], [3, 6, 7, 5], [9, 11, 13, 12] ]; const sumSmallest = (arr = []) => { const findSmallest = array => array.reduce((acc, val) => { return Math.min(acc, val); }, Infinity) let sum = 0; arr.forEach(sub => { sum += findSmallest(sub); }); return sum; }; console.log(sumSmallest(arr));Output18
Read MoreFinding the only out of sequence number from an array using JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers. The array is sorted in ascending / increasing order and only one element in the array is out of order.Our function should find and return that element.ExampleFollowing is the code −const arr = [1, 2, 3, 4, 17, 5, 6, 7, 8]; const findWrongNumber = (arr = []) > { for(let i = 0; i < arr.length - 1; i++){ const el = arr[i]; if(el - arr[i + 1] < 0 && arr[i + 1] - arr[i + 2] > 0){ return arr[i + 1]; } }; }; console.log(findWrongNumber(arr));Output17
Read MoreCounting the number of letters that occupy their positions in the alphabets for array of strings using JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of strings of english lowercase alphabets.Our function should map the input array to an array whose corresponding elements are the count of the number of characters that had the same 1-based index in the index as their 1-based index in the alphabets.For instance−This count for the string ‘akcle’ will be 3 because the characters ‘a’, ‘c’ and ‘e’ have 1-based index of 1, 3 and 5 respectively both in the string and the english alphabets.ExampleFollowing is the code − Live Democonst arr = ["abode", "ABc", "xyzD"]; const findIndexPairCount ...
Read MoreBreaking a string into chunks of defined length and removing spaces using JavaScript
ProblemWe are required to write a JavaScript function that takes in a string sentence that might contain spaces as the first argument and a number as the second argument.Our function should first remove all the spaces from the string and then break the string into a number of chunks specified by the second argument.All the string chunks should have the same length with an exception of last chunk, which might, in some cases, have a different length.ExampleFollowing is the code − Live Democonst num = 5; const str = 'This is an example string'; const splitString = (str = '', num ...
Read MoreConstructing an array of first n multiples of an input number in JavaScript
ProblemWe are required to write a JavaScript function that takes in two numbers, let say m and n.Our function should construct and return an array of first n natural multiples of m.ExampleFollowing is the code − Live Democonst m = 6; const n = 14; const firstNMultiple = (m = 1, n = 1) => { const res = []; for(let i = 1; i
Read MoreFinding the character with longest consecutive repetitions in a string and its length using JavaScript
ProblemWe are required to write a JavaScript function that takes in a string. Our function should return an array of exactly two elements the first element will be characters that makes the most number of consecutive appearances in the string and second will be its number of appearances.ExampleFollowing is the code − Live Democonst str = 'tdfdffddffsdsfffffsdsdsddddd'; const findConsecutiveCount = (str = '') => { let res=''; let count=1; let arr = [] for (let i=0;iv
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