Exercise 2 from Eloquent JavaScript

//Problem: Print out all numbers from 1 to 100. When divisible by 3 print Fizz, then divisible by 5 print Buzz, when divisible by both 3 and 5 print FizzBuzz
// Solution: JS - Loop through all the numbers, check modulo 3, 5 and 3 and 5, print appropriate word

function fizzBuzz(min, max) {
    
    function fizzOrBuzz (number, divisorA, divisorB) {
        if (divisorB) {
            return ((number % divisorA === 0) && (number % divisorB === 0))  
        } else {
            return number % divisorA === 0
        }
    }
    
    for (var i = min; i <= max; i++) {
        if (fizzOrBuzz(i, 3, 5)) {
            console.log('FizzBuzz (', i , ')');
        } else if (fizzOrBuzz(i, 3)) {
            console.log('Fizz (', i, ')');
        } else if (fizzOrBuzz(i, 5)) {
            console.log('Buzz (', i , ')');
        } else {
            console.log(i);
        }
    }
}

fizzBuzz(1, 100);

Exercise 3 from Eloquent JavaScript

// Problem: Draw out a chessboard of 8*8 using the space and # characters, alternating the start character. 
// Solution: JS - Use a loop to draw out the columns then at the end, alternate a boolean to start with one character or the other. 

function chessBoard(spread) {
    var blank = false;
    var a = ' ', b = '#', row = '';
    
    for (var c = 1; c <= spread*spread; c++) {
        if (c % spread === 0) {
            row += '\n'
        }
        else if(blank) {
            row += a;
            blank = !blank;
        } else {
            row += b
            blank = !blank;
        }
    }
    console.log(row);
}

chessBoard(8);

Exercise 4 from Eloquent JavaScript

// Problem: Return the minimum number between two numbers
// Solution: Accept two arguments and determime which is less

function min(a, b) {
    if (typeof(a) === 'number' && typeof(b) === 'number') {
        var min = a < b;
        return min ? a : b
    } else {
        return NaN;
    }   
}

console.log(min(3,-9));

Exercise 5 from Eloquent JavaScript

// Problem: Use recursion to determine whether a number is even, if even, return true
// Solution: Create a function that returns true if number is 0, false if number is 1, else subtract 2 from the number

function isEven(number){
    if(number < 0) {
        number = number * -1;
    }

    if (number === 0) {
        return true;
    } else if (number === 1) {
        return false;
    } else {
        number -= 2;
        return isEven(number);
    }
}

console.log(isEven(-34));

Exercise 6 from Eloquent JavaScript

// Problem: Create a function that counts how many times a provided letter appears in a string
// Solution: Loop through the string using .charAt to determine whether the letter is a match
function countChars(string, letter){
    var count = 0;
    for (var i = 0; i < string.length; i++) {
        if (string.charAt(i) === letter) {
            count+=1;
        }
    }
    return count;
}

console.log(countChars('chakkalakka', 'a'));

Calculate prime numbers in a range

function getPrimes(min, max) {

    function isPrimeBruteForce(number){
        for (var i = 2; i < (number - 1); i++) {
            if (number % i === 0) {
                return false;
            }
        }
        return true
    }

    if (min < max && min > 1 && max > 1) {
        var primes = [];
        
        for (var i = min; i < max; i++) {
            if(isPrimeBruteForce(i)) {
                primes.push(i);
            }
        }     
        return primes;
    } else {
        return -1;
    }
}

console.log(getPrimes(3, 100));

Exercise 7 from Eloquent JavaScript

function range(start, end, increment) {
    var arr = [];
    var inc = 1;
    if (increment) {
        inc = increment;
    } 
    for (var i = start; i <= end; i+=inc) {
        arr.push(i);
    }
    return arr;
}

function sum(array) {
    var sum = 0;
    for (var i = 0; i < array.length; i++) {
        sum = sum + array[i];
    }
    return sum;
}

console.log(sum(range(1,10, 2)));