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

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

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

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

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

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

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

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

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

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.

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


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

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

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

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

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

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 ]

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

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

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

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

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

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

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 ]

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' ]

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?...")); // [ '..........', '...' ]

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

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

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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