JavaScript - AlexLintu

Great JavaScript Resources

Web Development Path by CodeCademyEloquent JavaScript (3rd edition) by Marijn HaverbekeThe Net Ninja YouTube ChannelFireship YouTube ChannelcodeSTACKr YouTube ChannelHackerRankLeetCode

HackerRank

HackerRank Repeated String | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* param {string} s param {number} n returns {number} Number of `a` occurances */Test CasesrepeatedString('aba', 10); repeatedString('a', 1000000);Pseudo CodeLet's figure out how many times the string s will be repeated in our algorithm without remainder and record

HackerRank

HackerRank Two Strings | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* param {string} s1 param {string} s1 returns {string} 'YES' || 'NO' */Test CasetwoStrings('and', 'art'); twoStrings('be', 'cat');JavaScript Solutionfunction twoStrings(s1, s2) { let lettersMap = {}; for (const letter of s1) { if (!lettersMap[letter]) { lettersMap[letter] = 1; } } for (const letter of

Concepts

What is a Promise | JavaScript

A Promise is an object that represents an eventual outcome (success or failure) of an asynchronous operation and its resulting value. A promise is basically a placeholder for a value (outcome of operation) or an error (reason for failure) that we will receive at some point in the future, but

JavaScript

What is a Hash Map Data Structure | JavaScript

Hash Map is a non-linear data structure in computer science. Hash Maps act like key-value stores and are very efficient at saving and retrieving data. Hash Mapshash function - converts a key into an index within the hash map's underlying arrayhash collision - happens when a hash function returns the

JavaScript

HackerRank Inheritance | JS Solution

ProblemHackerRank detailed problem description can be found here. Sample InputRobot Bobert 5135617 2 100 80Sample OutputName: Bobert, Robot ID: 5135617 Grade: OJavaScript Solutionclass Student extends Person { /* * Class Constructor * * @param firstName - A string denoting the Person's first name. * @param lastName - A string denoting the Person's last name. * @param id

JavaScript

HackerRank 2D Arrays | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {array} arr - 6x6 2d array output {number} - maximum hourglass sum */Test Case let arr = [ [1, 1, 1, 0, 0, 0], [0, 1, 0, 0, 0, 0], [1, 1, 1, 0, 0, 0], [0, 0, 2, 4,

JavaScript

What is a Stack Data Structure | JavaScript

Stack is a last in, first out (LIFO) data structure in computer science. Stack is a linear collection of ordered data (nodes). Stackspush - add data to the top of the stack (first/head node)pop - remove and return data (first/head node) from the top of the stackpeek

JavaScript

HackerRank Dictionaries and Maps | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {string} '3\nsam 99912222\ntom 11122222\nharry 12299933\nsam\nedward\nharry' - 1st line: `n` number of entries in the phone book - `n` lines: `name phoneNumber` 2 space-separated values on a single line - unknown number of

JavaScript

HackerRank Arrays | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {array} arr output {string} */Test Casearr = [1,2,3,4,5];JavaScript Solutionfunction main() { const n = parseInt(readLine(), 10); const arr = readLine().split(' ').map(arrTemp => parseInt(arrTemp, 10)); // Solution #1 console.log(arr.reverse().toString(

JavaScript

HackerRank Let's Review | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {string} input output {string} 'even' 'odd' */Test Caseinput = '2\nHacker\nRank';JavaScript SolutionA bit of a 'gotcha' here is the fact that the string we receive as an input comes in with several new line breaks \n and

JavaScript

HackerRank Loops | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {number} n output {string} n x i = result */Test Casen = 5;JavaScript Solutionfunction main() { const n = parseInt(readLine(), 10); if (!n || typeof n !== 'number') { return; } for (let i = 1; i < 11; i++) { console.log(`${n} x ${i}

JavaScript

HackerRank Sales by Match | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* param {number} n param {array of numbers} ar returns {number} the total number of pairs */Test Case// Example used by HackerRank n = 9; ar = [10, 20, 20, 10, 10, 30, 50, 10, 20] // Visual example n = 9; ar = ['blue',

JavaScript

HackerRank Class vs Instance | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {number} age output {string} */Test Case// Different ages: 4, -1, 10, 16, 18JavaScript Solutionfunction Person(initialAge) { // Add some more code to run some checks on initialAge let age = 0; if (initialAge >= 0) { age = initialAge; } else { console.log(

JavaScript

HackerRank Conditional Statements | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* input {number} N output {string} 'Weird' || 'Not Weird' */Test CaseN = 24;JavaScript Solutionfunction main() { const N = parseInt(readLine(), 10); if (N % 2 === 0) { if ((N >= 2 && N <= 5) || N > 20) { console.log('Not Weird')

JavaScript

What is a Queue Data Structure | JavaScript

Queue is a first in, first out (FIFO) data structure in computer science. Imagine a line up at your favourite restaurant that works on first come, first serve basis. The first person to enter the line up, would be the first one to enter the restaurant. The last person to

JavaScript

HackerRank Operators | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/** * Calculate and print rounded to the nearest integer result. * @param {number} meal_cost * @param {number} tip_percent * @param {number} tax_percent * @print {number} result * @return {undefined} */Test Casemeal_cost = 15.00; tip_percent = 20; tax_percent = 13; solve(15.

Linked Lists

HackerRank Delete a Node from a Linked List | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* param {Node} head param {number} position return {Node} head */Test CaseInitial Linked ListResulting Linked ListJavaScript Solutionfunction deleteNode(head, position) { if (!head) { return null; } let nodeToDelete = head; if (position === 0) { head = nodeToDelete.next; return head; } let count = 0; let prev

JavaScript

HackerRank Data Types | JS Solution

ProblemHackerRank detailed problem description can be found here. Inputs & Outputs/* {string} readLine() #1 {string} readLine() #2 {string} readLine() #3 print {number} sum of `i` and `int` print {string} sum of `d` and `float` print {string} concat `s` and `str` */Test Caseint = parseInt('12'); float = parseFloat('4.0'); str = 'is

JavaScript

Linked List Cycle Detection | JS Solution

HackerRank detailed problem description can be found here. ProblemDetermine if a provided singly linked list has a cycle in it, meaning if any node is visited more than once while traversing the list. Inputs & Outputs/* param {Node} head return {number} 1 or 0 */Codefunction hasCycle(head) { if (!head) { return

HackerRank

HackerRank Insert a Node at a Specific Position in a Linked List | JS Solution

ProblemHackerRank detailed problem description can be found here. We need to create a function insertNodeAtPosition(head, data, position) {}. This function should: Create a new node using provided dataInsert that newly created node at the provided position inside a Singly Linked ListLastly, return the head nodeInputs & Outputs/* param {Node} head

HackerRank

HackerRank Left Rotation | JS Solution

1. ProblemGiven an array of numbers we need to rotate the numbers to the left n times. First number becomes last creating a circular array. 2. Testlet testArr = [3, 4, 5, 1, 2]; let testN = 3;3. Data Types & StructuresArray and number 4. Codefunction rotLeft(arr, n) { let counter

HackerRank

HackerRank Designer PDF Viewer | JS Solution

ProblemDetermine the area of the rectangle highlight in mm2 for a word, based on provided array of letter heights and letter width of 1mm. Input: array of numbers (26 character heights in consecutive alphabetical order / ascii[a-z]), string (a single word consisting of max of 10 lowercase English letters) Output:

HackerRank

HackerRank A Very Big Sum | JS Solution

1. ProblemInput: Array of numbers Output: A number Return a total sum of all of the numbers in the array. Keep in mind that the resulting sum might exceed the maximum range allowed. 2. Edge Cases / Test Caseslet testArr = [1000000001, 1000000002, 1000000003, 1000000004, 1000000005];3. Data Types / Structures / Big O