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Javascript Articles
Page 380 of 534
Validating email and password - JavaScript
Suppose, we have this dummy array that contains the login info of two of many users of a social networking platform −const array = [{ email: 'usman@gmail.com', password: '123' }, { email: 'ali@gmail.com', password: '123' } ];We are required to write a JavaScript function that takes in an email string and a password string.The function should return a boolean based on the fact whether or not the user exists in the database.ExampleFollowing is the code −const array = [{ email: 'usman@gmail.com', password: '123' }, { email: 'ali@gmail.com', password: '123' }]; const matchCredentials ...
Read MoreThe Zombie Apocalypse case study - JavaScript
A nasty zombie virus is spreading out in the digital cities. We work at the digital CDC and our job is to look over the city maps and tell which areas are contaminated by the zombie virus so the digital army would know where to drop the bombs.They are the new kind of digital zombies which can travel only in vertical and horizontal directions and infect only numbers same as them.We'll be given a two-dimensional array with numbers in it.For some mysterious reason patient zero is always found in north west area of the city (element [0][0] of the matrix) ...
Read MoreFilter one array with another array - JavaScript
Suppose, we have an array and objects like the following −const main = [ {name: "Karan", age: 34}, {name: "Aayush", age: 24}, {name: "Ameesh", age: 23}, {name: "Joy", age: 33}, {name: "Siddarth", age: 43}, {name: "Nakul", age: 31}, {name: "Anmol", age: 21}, ]; const names = ["Karan", "Joy", "Siddarth", "Ameesh"];We are required to write a JavaScript function that takes in two such arrays and filters the first array in place to contain only those objects whose name property is included in the second array.ExampleFollowing is the code −const main = [ {name: "Karan", ...
Read MoreHow to insert an element into all positions in an array using recursion - JavaScript?
We are required to declare a function, let’s say insertAllPositions, which takes two arguments −an element, x, and an array, arr. Functions must return an array of arrays, with each array corresponding to arr with x inserted in a possible position.That is, if arr is the length N, then the result is an array with N + 1 arrays −For example, the result of insertAllPositions(10, [1, 2, 3]) should be −const output = [ [10, 1, 2, 3], [1, 10, 2, 3], [1, 2, 10, 3], [1, 2, 3, 10] ];We are required to write this ...
Read MoreHow can we make an Array of Objects from n properties of n arrays in JavaScript?
Suppose we have two arrays of literals like these −const options = ['A', 'B', 'C', 'D']; const values = [true, false, false, false];We are required to write a JavaScript function that creates and returns a new Array of Objects from these two arrays, like this −const response = [ {opt: 'A', val: true}, {opt: 'B', val: false}, {opt: 'C', val: false}, {opt: 'D', val: false}, ];ExampleFollowing is the code −const options = ['A', 'B', 'C', 'D']; const values = [true, false, false, false]; const mapArrays = (options, values) => { const res = []; ...
Read MoreReturn 5 random numbers in range, first number cannot be zero - JavaScript
We are required to write a JavaScript function that generates an array of exactly five unique random numbers. The condition is that all the numbers have to be in the range [0, 9] and the first number cannot be 0.ExampleFollowing is the code −const fiveRandoms = () => { const arr = [] while (arr.length < 5) { const random = Math.floor(Math.random() * 10); if (arr.indexOf(random) > -1){ continue; }; if(!arr.length && !random){ continue; } arr[arr.length] = random; } return arr; }; console.log(fiveRandoms());OutputThis will produce the following output in console −[ 9, 0, 8, 5, 4 ]
Read MoreHow to replace leading zero with spaces - JavaScript
We are required to write a JavaScript function that takes in a string that represents a number. Replace the leading zero with spaces in the number. We need to make sure the prior spaces in number are retained.For example,If the string value is defined as −" 004590808"Then the output should come as −" 4590808"ExampleFollowing is the code −const str = ' 004590808'; const replaceWithSpace = str => { let replaced = ''; const regex = new RegExp(/^\s*0+/); replaced = str.replace(regex, el => { const { length } = el; return ' '.repeat(length); }); return replaced; }; console.log(replaceWithSpace(str));OutputThis will produce the following output in console −4590808
Read MoreTrying to get number for each character in string - JavaScript
We are required to write a JavaScript function that takes in a string. It should print out each number for every corresponding letter in the string.For example, a = 1 b = 2 c = 3 d = 4 e = 5 . . . Y = 25 Z = 26Therefore, if the input is "hello man", Then the output should be a number for each character −"8, 5, 12, 12, 15, 13, 1, 14"ExampleFollowing is the code −const str = 'hello man'; const charPosition = str => { str = str.split(''); const arr = []; const ...
Read MoreHow to get the numbers which can divide all values in an array - JavaScript
We are required to write a JavaScript function that takes in an array of numbers and returns a number which can exactly divide all the numbers in the array.Let’s say the following is our array −const arr = [4, 6, 34, 76, 78, 44, 34, 26, 88, 76, 42];ExampleFollowing is the code −const arr = [4, 6, 34, 76, 78, 44, 34, 26, 88, 76, 42]; const dividesAll = el => { const result = []; let num; for (num = Math.floor(el / 2); num > 1; num--){ if (el % num === 0) { result.push(num); } }; return result; }; const dividesArray = arr => { return arr.map(dividesAll).reduce((acc, val) => { return acc.filter(el => val.includes(el)); }); }; console.log(dividesArray(arr));OutputThis will produce the following output in console −[ 2 ]
Read MoreSorting Array with JavaScript reduce function - JavaScript
We are required to write a JavaScript function that takes in an array of numbers. The function should sort the array with using the Array.prototype.sort() method. We are required to use the Array.prototype.reduce() method to sort the array.Let’s say the following is our array −const arr = [4, 56, 5, 3, 34, 37, 89, 57, 98];ExampleFollowing is the code −// we will sort this array but // without using the array sort function // without using any kind of conventional loops // using the ES6 function reduce() const arr = [4, 56, 5, 3, 34, 37, 89, 57, 98]; const ...
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