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Web Development Articles
Page 45 of 801
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 −const exp = '6 - 4'; const findResult = (exp = '') => { const digits = '0123456789.'; const operators = ['+', '-', '*', '/', 'negate']; const legend = { '+': { pred: 2, func: (a, ...
Read MoreCalculating variance for an array of numbers in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers sorted in increasing order.Our function should calculate the variance for the array of numbers. Variance of a set of numbers is calculated on the basis of their mean.$Mean (M) = ( \sum_{i=0}^{n-1} arr[i])$ / nAnd variance (V) = $(\sum_{i=0}^{n-1} (arr[i] - M)^2)$ / nExampleFollowing is the code −const arr = [4, 6, 7, 8, 9, 10, 10]; const findVariance = (arr = []) => { if(!arr.length){ return 0; }; const sum = arr.reduce((acc, val) => acc + val); ...
Read MoreSorting binary string having an even decimal value using JavaScript
ProblemWe are required to write a JavaScript function that takes in a string that contains binary strings of length 3 all separated by spaces.Our function should sort the numbers in ascending order but only order the even numbers and leave all odd numbers in their place.ExampleFollowing is the code −const str = '101 111 100 001 010'; const sortEvenIncreasing = (str = '') => { const sorter = (a, b) => { const findInteger = bi => parseInt(bi, 2); if(findInteger(a) % 2 === 1 || findInteger(b) % 2 === 1){ return 0; }; return findInteger(a) - findInteger(b); }; const res = str .split(' ') .sort(sorter) .join(' '); return res; }; console.log(sortEvenIncreasing(str));Output101 111 100 001 010
Read MoreCalculating and adding the parity bit to a binary using JavaScript
Parity BitA parity bit, or check bit, is a bit added to a string of bits to ensure that the total number of 1-bits in the string is even or odd.ProblemWe are required to write a JavaScript function that takes in two parameters, one being the wanted parity (always 'even' or 'odd'), and the other being the binary representation of the number we want to check.The task of our function is to return an integer (0 or 1), which is the parity bit we need to add to the binary representation so that the parity of the resulting string is ...
Read MoreSumming cubes of natural numbers within a range in JavaScript
ProblemWe are required to write a JavaScript function that takes in a range array of two numbers. Our function should find the sum of all the cubes of the numbers that falls in the specified range.ExampleFollowing is the code −const range = [4, 11]; const sumCubes = ([l, h]) => { const findCube = num => num * num * num; let sum = 0; for(let i = l; i
Read MoreImplementing a custom function like Array.prototype.filter() function in JavaScript
ProblemWe are required to write a JavaScript function that lives on the prototype Object of the Array class.Our function should take in a callback function as the only argument. This callback function should be called for each element of the array.And that callback function should take in two arguments the corresponding element and its index. If the callback function returns true, we should include the corresponding element in our output array otherwise we should exclude it.ExampleFollowing is the code −const arr = [5, 3, 6, 2, 7, -4, 8, 10]; const isEven = num => num % 2 === 0; ...
Read MoreCounting number of triangle sides in an array in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers, arr, as the first and the only argument.The task of our function is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.For example, if the input to the function is −const arr = [2, 2, 3, 4];Then the output should be −const output = 3;Output ExplanationValid combinations are:2, 3, 4 (using the first 2) 2, 3, 4 (using the second 2) 2, 2, 3ExampleFollowing is the code −const arr = ...
Read MoreFinding the 1-based index of a character in alphabets using JavaScript
ProblemWe are required to write a JavaScript function that takes in a lowercase English alphabet character. Our function should return the character’s 1-based index in the alphabets.ExampleFollowing is the code −const char = 'j'; const findCharIndex = (char = '') => { const legend = ' abcdefghijklmnopqrstuvwxyz'; if(!char || !legend.includes(char) || char.length !== 1){ return -1; }; return legend.indexOf(char); }; console.log(findCharIndex(char));Output10
Read MoreConstructing an array of addition/subtractions relative to first array element in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of positive integers. Our function should map this array to an array of string integers.The array should contain the number we should add/subtract to the first element to achieve the corresponding element.For example[4, 3, 6, 2]should return −['+0', '-1', '+2', '-2']ExampleFollowing is the code −const arr = [4, 3, 6, 2]; const buildRelative = (arr = []) => { const res = []; let num = ''; for(let i of arr){ if(i - arr[0] >= 0){ num ...
Read MoreGenerating desired pairs within a range using JavaScript
ProblemWe are required to write a JavaScript function that takes in a number n. Our function should generate an array containing the pairs of integers [a, b] that satisfy the following conditions −0
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