JavaScript Coding Challenges

01. Creates a function that takes two numbers as arguments and return their sum.

function addition(a, b) {
    //Write Your solution Here
};

console.log(addition(10, 20)); // 30
console.log(addition(30, 20)); // 50
console.log(addition(10, 90)); // 100

Solution

function addition(a, b) {
    let add = a + b;
    return (add)
};

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02. Converts hours into seconds.

function howManySeconds(hours) {
    //Write Your solution Here
};


console.log(howManySeconds(12)); // 43200
console.log(howManySeconds(8)); // 28800
console.log(howManySeconds(3)); // 10800

Solution

function howManySeconds(hours) {
    let hoursToSeconds = (hours*3600);
    return(hoursToSeconds)
};

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03. Converts minutes into seconds.

function convert(minutes){
    //Write Your solution Here
};


console.log(convert(30)); // 1800
console.log(convert(10)); // 600
console.log(convert(20)); // 1200

Solution

function convert(minutes) {
    let seconds = minutes*60;
    return (seconds)
};

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04. Calculates total points of a team from number of wins(3pts), draws(1pt), and losses(0pt).

function footballPoints(wins, draws, losses){
    //Write Your solution Here
};


console.log(footballPoints(4, 3, 1)); // 15
console.log(footballPoints(10, 5, 0)); // 35
console.log(footballPoints(11, 0, 9)); // 33

Solution

function footballPoints(wins, draws, losses) {
    let points = (wins*3) + (draws*1) + (losses*0)
    return(points)
};

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05. Write functions to calculate the bitwise AND, bitwise OR and bitwise XOR of two numbers.

function bitwiseAND(n1, n2) {
    //Write Your solution Here
};

function bitwiseOR(n1, n2) {
    //Write Your solution Here
};

function bitwiseXOR(n1, n2) {
    //Write Your solution Here
};


console.log(bitwiseAND(10, 20)); // 0
console.log(bitwiseOR(10, 20)); // 30
console.log(bitwiseXOR(10, 20)); // 30

Solution

function bitwiseAND(n1, n2) {
    let answer = n1 & n2;
    return (answer);
};

function bitwiseOR(n1, n2) {
    let answer = n1 | n2;
    return (answer);
};

function bitwiseXOR(n1, n2) {
    let answer = n1 ^ n2;
    return (answer);
};

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06. Write Function to return first value of an array.

function getFirstValue(arr) {
      //Write Your solution Here
};


console.log(getFirstValue(["Saab", "Volvo", "BMW"])); // Saab
console.log(getFirstValue([3, 5, 1])); // 3
console.log(getFirstValue(['hello', 'world', 'welcome'])); // hello

Solution

function getFirstValue(arr) {
    return arr[0];
};

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07. Create a function that takes a number as an argument, increments the number by +1 and returns the result.

function addition(num){
      //Write Your solution Here
};


console.log(addition(5)); // 6
console.log(addition(100)); // 101
console.log(addition(99)); // 100

Solution

function addition(num) {
    let numPlusOne = num + 1;
    return(numPlusOne)
};

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08. Given two numbers, return true if the sum of both numbers is less than 100. Otherwise return false.

function lessThan100(a, b){
      //Write Your solution Here
};


console.log(lessThan100(10, 20)); // true
console.log(lessThan100(50, 60)); // false
console.log(lessThan100(20, 50)); // true

Solution

function lessThan100(a, b) {
    if (a + b < 100) {
        return true;
    }
    else {
        return false;
    }
};

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09. Create a function that returns true when num1 is equal to num2; otherwise return false.

function isSameNum(num1, num2){
      //Write Your solution Here
};


console.log(isSameNum(30, 30)); // true
console.log(isSameNum(20, 40)); // false
console.log(isSameNum(50, 50)); // true

Solution

function isSameNum(num1, num2) {
    if (num1 === num2){
        return true;
    }
    else {
        return false;
    }
};

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10. Create a function that takes a number (step) as an argument and returns the amount of matchsticks in that step.

JavaScript Coding Challenges jahidul islam zim

function matchHouses(step){
      //Write Your solution Here
};


console.log(matchHouses(5)); // 26
console.log(matchHouses(0)); // 0
console.log(matchHouses(10)); // 51

Solution

function matchHouses(step){
    if (step > 0) {
        let matchSticks = ((step*6) - (step -1));
    return(matchSticks)
    }
    else {
        let matchSticks = 0;
        return (matchSticks)
    }
};

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11. Write function to return the square of a number.

function squared(a){
      //Write Your solution Here
};



console.log(squared(6)); // 36
console.log(squared(9)); // 81
console.log(squared(4)); // 16

Solution

function squared(a) {
    return (a*a);
};

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12. Write function to calc area of a rectangle

function findPerimeter(height, width){
      //Write Your solution Here
};


console.log(findPerimeter(20, 50)); // 140
console.log(findPerimeter(80, 30)); // 220
console.log(findPerimeter(10, 40)); // 100

Solution

function findPerimeter(height, width){
    let perimeter = 2*(height + width);
    return (perimeter)
};

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13. Add up all the numbers from 1 to the number you passed to the function.

function addUp(num){
      //Write Your solution Here
};


console.log(addUp(10)); // 55
console.log(addUp(40)); // 820
console.log(addUp(15)); // 120

Solution

function addUp(num) {
    let sum = 0;
    for (i = 0; i <= num; i++){
        sum += i;
            }
    return(sum)
};

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14. Create a function that takes in three arguments (prob, prize, pay) and returns true if prob * prize > pay; otherwise return false.

function profitableGamble(prob, prize, pay){
      //Write Your solution Here
};


console.log(profitableGamble(2, 10, 20)); // false
console.log(profitableGamble(5, 10, 40)); // true
console.log(profitableGamble(6, 3, 30)); // false

Solution

function profitableGamble(prob, prize, pay){
    if (prob*prize > pay) {
        return (true)
    }
    else {
        return (false)
    }
};

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15. Takes an array of numbers, returns both the minimum and maximum numbers, in that order.

function minMax(arr){
      //Write Your solution Here
};


console.log(minMax([2, -1, 5])); // [ -1, 5 ]
console.log(minMax([0, 5, 2])); // [ 0, 5 ]
console.log(minMax([2, -5, -1])); // [ -5, 2 ]

Solution

function minMax(arr){
    arr.sort(function(a, b){return(a - b)})
    return [arr[0], arr[arr.length - 1]]
};

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16. Create a function that returns true if the first array can be nested inside the second.

arr1 can be nested inside arr2 if:

arr1's min is greater than arr2's min.

arr1's max is less than arr2's max.

function canNest(arr1, arr2){
      //Write Your solution Here
};


console.log(canNest([3, 1], [4, 0])); // true
console.log(canNest([9, 9, 8], [8, 9])); // false
console.log(canNest([1, 2, 3, 4], [0, 6])); // true

Solution

function canNest(arr1, arr2) {
    arr1.sort(function(a,b){return(a - b)});
    arr2.sort(function(a,b){return(a - b)});
    let arr1MinMax = [arr1[0], arr1[arr1.length -1]];
    let arr2MinMax = [arr2[0], arr2[arr2.length -1]];
    if (arr1MinMax[0] > arr2MinMax[0] && arr1MinMax[1] < arr2MinMax[1]){
        return true
    }
    else{
        return false
        }
};

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17. Create a function that calculates the number of different squares in an n * n square grid.

function numberSquares(n){
      //Write Your solution Here
};


console.log(numberSquares(4)); // 30
console.log(numberSquares(5)); // 55
console.log(numberSquares(6)); // 91

Solution

function numberSquares(n){
    let num = n*(2*n + 1)*(n + 1)/6
    return (num)
};

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18. Your function will be passed two functions, f and g, that don't take any parameters. Your function has to call them, and return a string which indicates which function returned the larger number.

If f returns the larger number, return the string f.

If g returns the larger number, return the string g.

If the functions return the same number, return the string neither.

function whichIsLarger(f, g){
      //Write Your solution Here
};


console.log(whichIsLarger(() => 25, () => 15)); // f
console.log(whichIsLarger(() => 25, () => 25)); // neither
console.log(whichIsLarger(() => 25,  () => 50)); // g

Solution

function whichIsLarger(f, g){
    if (f() > g()) {
        return ('f')
    }
    else if (g() > f()) {
        return ('g')
    }
    else if (f() === g()) {
        return ('neither')
    }
};

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19. Christmas Eve is almost upon us, so naturally we need to prepare some milk and cookies for Santa! Create a function that accepts a Date object and returns true if it's Christmas Eve (December 24th) and false otherwise. Keep in mind JavaScript's Date month is 0 based, meaning December is the 11th month while January is 0.

function timeForMilkAndCookies(date){
      //Write Your solution Here
};


console.log(timeForMilkAndCookies(new Date(3000, 11, 24))); //true
console.log(timeForMilkAndCookies(new Date(2013, 0, 23))); //false
console.log(timeForMilkAndCookies(new Date(3000, 11, 24))); //true

Solution

function timeForMilkAndCookies(date){
    return date.getMonth() === 11 && date.getDate() === 24;
};

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20. function that takes a two-digit number and determines if it's the largest of two possible digit swaps.

function largestSwap(num){
      //Write Your solution Here
};


console.log(largestSwap(14)); //false
console.log(largestSwap(53)); //true
console.log(largestSwap(-27)); //false

Solution

function largestSwap(num){
    let num1 = num + "";
    let num2 = num1.split("").reverse().join("");
    if (num1 >= num2) {
        return true;
    }
    if (num1 < num2) {
        return false;
    }
};


function largestSwap(num) {
    let c = num.toString();
    let a = [];
    let b = 0;
    for (let i = 0; i < c.length; i++) {
      a.push(c[c.length - 1 - i]);
      b += a[i];
    }
    let d = parseInt(b);
    if (d > num) {
      return false;
    } else return true;
};

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21. function that takes two strings as arguments and returns the number of times the first string (the single character) is found in the second string.

function charCount(myChar, str){
      //Write Your solution Here
};


console.log(charCount("a", "largest")); //1
console.log(charCount("c", "Chamber of secrets")); // 2
console.log(charCount("b", "big fat bubble")); //4

Solution

function charCount(myChar, str){
    let a = 0;
    for (let i = 0; i < str.length; i++) {
      if (myChar.toLowerCase() === str.toLowerCase()[i]) {
        a += 1;
      }
    }
    return a
};

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22. function that takes two parameters and repeats the string n number of times.

function repetition(txt, n){
      //Write Your solution Here
};


console.log(repetition('zim', 5)); //zimzimzimzimzim
console.log(repetition('zoy', 2)); //zoyzoy
console.log(repetition('akib', 7)); //akibakibakibakibakibakibakib

Solution

function repetition(txt, n){
    let reptxt = ""
    while (n > 0) {
        reptxt += txt
        n--;
    }
    return reptxt
};

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23. function that takes an array of non-negative integers and strings and return a new array without the strings.

function filterArray(arr){
      //Write Your solution Here
};


console.log(filterArray([1, 'z', 4, 5, 'i', 9, 'm'])); //[ 1, 4, 5, 9 ]
console.log(filterArray([8, 'z', 1, '8', 'i', 9, 'm'])); //[ 8, 1, 9 ]
console.log(filterArray([7, '1', 'z', 0, 'i', 9, 'm'])); //[ 7, 0, 9 ]

Solution

function filterArray(arr){
    let filteredArray = arr.filter(item => typeof item === "number");
    return filteredArray
};



function filterArray(arr) {
    let filteredArr = [];
    for (let i = 0; i < arr.length; i++) {
      if ( typeof arr[i] !== "string") {
        filteredArr.push(arr[i])
      } 
    } return filteredArr
};

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24. Write a function that take a string and write a regular expression inner function that returns the value that matches every red flag and blue flag in this string.

function matchFlag(str){
      //Write Your solution Here
};


console.log(matchFlag("yellow flag red flag blue flag green flag")); //[ 'red flag', 'blue flag' ]
console.log(matchFlag("yellow flag green flag orange flag white flag")); //null
console.log(matchFlag("yellow flag blue flag green flag")); //[ 'blue flag' ]

Solution

function matchFlag(str){
    let REGEXP = /red flag|blue flag/g;
    return str.match(REGEXP);
};

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25. Write a function that take a string and write a RegExp to find ellipsis: 3 (or more?) dots in a row in this string.

function matchEllipsis(str){
      //Write Your solution Here
};


console.log(matchEllipsis("Hello!... How goes?.....")); //[ '...', '.....' ]
console.log(matchEllipsis("good morning!..... How goes?.")); // [ '.....' ]
console.log(matchEllipsis("good night!.......... How goes?...")); // [ '..........', '...' ]

Solution

function matchEllipsis(str){
    let REGEXP = /\.{3,}/g;
    return str.match(REGEXP);
};

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26. Write a function that returns 0 if the input is 1, and returns 1 if the input is 0. Try completing this challenge without using any:

Conditionals

Ternary operators

Negations

Bit operators

function flip(y){
      //Write Your solution Here
};


console.log(flip(1)); // 0
console.log(flip(0)); // 1

Solution

function flip(y){
    let x = y - 1;
    return (Math.abs(x))
};

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27. Create a function that takes a string and returns a string in which each character is repeated once.

function doubleChar(str){
      //Write Your solution Here
};


console.log(doubleChar('jahidul')); //jjaahhiidduull
console.log(doubleChar('islam')); //iissllaamm
console.log(doubleChar('zim')); //zziimm

Solution

function doubleChar(str) {
    let doubleString = '';
    for(let i=0; i<str.length; i++){
        doubleString += str[i] + str[i]
    }
    return doubleString
};

function doubleChar(str){
    let array = str.split("");
    let array2 = array.map( x => x.repeat(2));
    let doubleString = array2.join("");
    return doubleString
};

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28. Write a function that takes a positive integer and return its factorial.

function factorial(num){
      //Write Your solution Here
};



console.log(factorial(5)); //120
console.log(factorial(10));  //3628800
console.log(factorial(8)); //40320

Solution

function factorial(num) {
    let fact = 1;
    for (let i = 0; i<num ; i++){
        fact *= (num-i);
    }
    return fact
};

function factorial(num){
    if (num < 0)
        return -1;
    else if (num == 0)
        return 1;
    else {
        return (num * factorial(num - 1));
    }
};

function factorial(num){
  let result = num;
  if (num === 0 || num === 1) return 1;
  while (num > 1) {
    num--;
    result *= num;
  }
  return result;
};

function factorial(num){
    let fact = num;
    if (num === 0 || num === 1) return 1;
    for (let i = num - 1; i >= 1; i--) {
      fact *= i;
    }
    return fact;
};

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29. Take an array of integers (positive or negative or both) and return the sum of the absolute value of each element.

function getAbsSum(arr){
      //Write Your solution Here
};


console.log(getAbsSum([1, -4, 3, 8, 0])); // 16
console.log(getAbsSum([1, 3, 0, -8, 0])); // 12
console.log(getAbsSum([1, -4, -3, 8, 0])); //16

Solution

function getAbsSum(arr){
  let absSum = 0;
  for (var i = 0; i < arr.length; i++) {
    absSum += Math.abs(arr[i]);
  }
  return absSum;
};

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30. Write a function that take a string and write a REGEXP that matches any characters except letters, digits and spaces.

function matchAny(str){
      //Write Your solution Here
};


console.log(matchAny('Csxdzontains_underscore ')); //[ '_' ]
console.log(matchAny('Csxdzontains_underscore $ * P')); //[ '_', '$', '*' ]

Solution

function matchAny(str){
    const REGEXP = /[^a-z0-9 ]/gi;
    return str.match(REGEXP)
};

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31. Create a function that takes a string and returns the number (count) of vowels contained within it.

function countVowels(str){
      //Write Your solution Here
};

console.log(countVowels('Jahidul Islam zim')); // 6
console.log(countVowels('returns the number of vowels')); // 8
console.log(countVowels('JavaScript Coding Challenges')); // 8

Solution

function countVowels(str){
    let count = 0;
    let vowlStr = str.toLowerCase().match(/(a|e|i|o|u)/g);
    for (let i = 0; i < vowlStr.length; i++) {
        count += 1;
    }
    return count;
};

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32. Create a function that takes two vectors as arrays and checks if the two vectors are orthogonal or not. The return value is boolean. Two vectors a and b are orthogonal if their dot product is equal to zero.

function isOrthogonal(arr1, arr2){
      //Write Your solution Here
};


console.log(isOrthogonal([1, -2, 4], [2, 5, 2])); //true
console.log(isOrthogonal([1, -2, 5], [2, 5, 2])); //false
console.log(isOrthogonal([1, 2, 4], [-2, 5, -2])); //true

Solution

function isOrthogonal(arr1, arr2){
    let ortho = 0;
    for (i = 0; i < arr1.length; i++){
        ortho += arr1[i]*arr2[i]
    }
    if (ortho === 0) {
        return true
    }
    return false
};

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33. Given an object of how many more pages each ink color can print, output the maximum number of pages the printer can print before any of the colors run out.

function inkLevels(inks){
      //Write Your solution Here
};


console.log(inkLevels({ cyan: 50, magenta: 12, yellow: 60 })); // 12
console.log(inkLevels({ cyan: 50, magenta: 120, yellow: 60 })); // 50
console.log(inkLevels({ cyan: 50, magenta: 12, yellow: 8 })); // 8

Solution

function inkLevels(inks){
  return Math.min(...Object.values(inks));
};

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34. Create a function that takes a string and returns a new string with all vowels removed.

function removeVowels(str){
      //Write Your solution Here
};

console.log(removeVowels('Jahidul Islam Zim')); //Jhdl slm Zm
console.log(removeVowels('a new string with all vowels')); // nw strng wth ll vwls
console.log(removeVowels('Create a function')); //Crt  fnctn

Solution

function removeVowels(str){
    let newArr = str.match(/[^aeiouAEIOU]/g);
    let newString = newArr.join('');
    return newString
};

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35. Create a function that takes an array of arrays with numbers. Return a new (single) array with the largest numbers of each.

function findLargestNums(arr){
      //Write Your solution Here
};


console.log(findLargestNums([[3,6], [10, 20], [-1, 7]])); //[ 6, 20, 7 ]
console.log(findLargestNums([[8,6], [1, 0], [10, -7]])); //[ 8, 1, 10 ]
console.log(findLargestNums([[3,34], [10, 22], [-1, -7]])); //[ 34, 22, -1 ]

Solution

function findLargestNums(arr){
    let newArr = []
    for (let i = 0; i < arr.length; i++) {
        newArr.push(Math.max(...arr[i]));
    }
    return newArr
};

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36. Given an array of scrabble tiles, create a function that outputs the maximum possible score a player can achieve by summing up the total number of points for all the tiles in their hand. Each hand contains 7 scrabble tiles.

function maximumScore(tileHand){
      //Write Your solution Here
};


console.log(
  maximumScore([
    { tile: "N", score: 1 },
    { tile: "K", score: 5 },
    { tile: "Z", score: 10 },
  ])
); //16

console.log(
  maximumScore([
    { tile: "N", score: 9 },
    { tile: "K", score: 5 },
    { tile: "Z", score: 40 },
  ])
); //54

console.log(
  maximumScore([
    { tile: "N", score: 1 },
    { tile: "K", score: 65 },
    { tile: "Z", score: 10 },
  ])
); //76

Solution

function maximumScore(tileHand){
  let score = 0;
  for ( let i = 0; i < tileHand.length; i++) {
    score += tileHand[i].score;
  }
  return score;
};

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37. Assume a program only reads .js or .jsx files. Write a function that accepts a file path and returns true if it can read the file and false if it can't.

function isJS(path){
      //Write Your solution Here
};

console.log(isJS('file.jsx')); //true 
console.log(isJS('file.jsg')); //false
console.log(isJS('file.js')); //true

Solution

function isJS(path){
    let extension = path.match( /[^.]+$/g)[0]
    if(extension === 'js' || extension==='jsx'){
        return true;
    }
    return false;
};

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JavaScript Coding Challenges

01. Creates a function that takes two numbers as arguments and return their sum.

02. Converts hours into seconds.

03. Converts minutes into seconds.

04. Calculates total points of a team from number of wins(3pts), draws(1pt), and losses(0pt).

05. Write functions to calculate the bitwise AND, bitwise OR and bitwise XOR of two numbers.

06. Write Function to return first value of an array.

07. Create a function that takes a number as an argument, increments the number by +1 and returns the result.

08. Given two numbers, return true if the sum of both numbers is less than 100. Otherwise return false.

09. Create a function that returns true when num1 is equal to num2; otherwise return false.

10. Create a function that takes a number (step) as an argument and returns the amount of matchsticks in that step.

11. Write function to return the square of a number.

12. Write function to calc area of a rectangle

13. Add up all the numbers from 1 to the number you passed to the function.

14. Create a function that takes in three arguments (prob, prize, pay) and returns true if prob * prize > pay; otherwise return false.

15. Takes an array of numbers, returns both the minimum and maximum numbers, in that order.

16. Create a function that returns true if the first array can be nested inside the second.

arr1 can be nested inside arr2 if:

arr1's min is greater than arr2's min.

arr1's max is less than arr2's max.

17. Create a function that calculates the number of different squares in an n * n square grid.

18. Your function will be passed two functions, f and g, that don't take any parameters. Your function has to call them, and return a string which indicates which function returned the larger number.

If f returns the larger number, return the string f.

If g returns the larger number, return the string g.

If the functions return the same number, return the string neither.

20. function that takes a two-digit number and determines if it's the largest of two possible digit swaps.

21. function that takes two strings as arguments and returns the number of times the first string (the single character) is found in the second string.

22. function that takes two parameters and repeats the string n number of times.

23. function that takes an array of non-negative integers and strings and return a new array without the strings.

24. Write a function that take a string and write a regular expression inner function that returns the value that matches every red flag and blue flag in this string.

25. Write a function that take a string and write a RegExp to find ellipsis: 3 (or more?) dots in a row in this string.

26. Write a function that returns 0 if the input is 1, and returns 1 if the input is 0. Try completing this challenge without using any:

Conditionals

Ternary operators

Negations

Bit operators

27. Create a function that takes a string and returns a string in which each character is repeated once.

28. Write a function that takes a positive integer and return its factorial.

29. Take an array of integers (positive or negative or both) and return the sum of the absolute value of each element.

30. Write a function that take a string and write a REGEXP that matches any characters except letters, digits and spaces.

31. Create a function that takes a string and returns the number (count) of vowels contained within it.

32. Create a function that takes two vectors as arrays and checks if the two vectors are orthogonal or not. The return value is boolean. Two vectors a and b are orthogonal if their dot product is equal to zero.

33. Given an object of how many more pages each ink color can print, output the maximum number of pages the printer can print before any of the colors run out.

34. Create a function that takes a string and returns a new string with all vowels removed.

35. Create a function that takes an array of arrays with numbers. Return a new (single) array with the largest numbers of each.

36. Given an array of scrabble tiles, create a function that outputs the maximum possible score a player can achieve by summing up the total number of points for all the tiles in their hand. Each hand contains 7 scrabble tiles.

37. Assume a program only reads .js or .jsx files. Write a function that accepts a file path and returns true if it can read the file and false if it can't.

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