arrays and loops

main.js

// 1.
// Without logging the values, list the value of `sports` and `total`
var sports = ['soccer', 'baseball'];
var total = sports.push('football', 'swimming');
// A:
// sports = ['soccer', 'baseball'];
// total = ['soccer', 'baseball', 'football', 'swimming']


// 2.
// Using the `strings` array, wrte a function `longestString()`
// that accepts an array argument and returns the longest string in the array
var strings = ['this','is','a','collection','of','words'];
// A:

// array -> str
function longestString(arrayOfStrings){
    var longestWord = "";

    for (var x=0; x<arrayOfStrings.length; x++){
        var currentElement = arrayOfStrings[x];
        if (currentElement.length > longestWord.length)
            longestWord = currentElement;
    }
    return longestWord;
}

console.assert(longestString(strings) === 'collection', {"message": "longestString should return 'collection'"});


// Use the `numbers` array for questions 3 - 8.
var numbers = [1,12,4,18,9,7,11,3,101,5,6];



// 3.
// Write a function `smallestNumber()` that accepts an array
// and returns the smallest number in the array.
// A:

// array -> number

function smallestNumber(arrayOfNumbers){
    var smallestNum = arrayOfNumbers[0];
    for (var x = 0; x < arrayOfNumbers.length; x++){
        var currentNum = arrayOfNumbers[x];
        if (currentNum < smallestNum){
            smallestNum = currentNum;
        }
    }
    return smallestNum;
}

console.assert(smallestNumber(numbers) === 1, {"message": "smallestNumber should return 1"});


// 4.
// Write a function `getEvens()` that accepts an array
// and returns only the even numbers in the array.
// A:

//array -> array
function getEvens(arrayOfNumbers){
    var evenArray = [];

    for(var i = 0; i<arrayOfNumbers.length; i++){
        var currentElement = arrayOfNumbers[i];
        if (currentElement % 2 == 0){
            evenArray.push(currentElement);
        }
    }

    //if the currentelement matches some condition (even), add it to evenArray
    return evenArray;
}


console.assert(getEvens(numbers).toString() === '12,4,18,6', {'message': 'getEvens should return "12,4,18,6"'});


// 5.
// Write a function that accepts an array argument
// and returns the array reversed
// Hint: When looping over the array, start at the last index
// and decrement the iterator to zero
// A:

//array -> array

function arrayReverser(arrayOfNumbers){
    var reversedArray = [];
    //loop over everynumber starting at the end,
    //push each number to the reversedArray;

    for(var i=arrayOfNumbers.length-1 ; i>=0 ; i-- ){
        var currentElement = arrayOfNumbers[i];
        reversedArray.push(currentElement)
    }    
    return reversedArray;
}


console.assert(arrayReverser(numbers).toString() === '6,5,101,3,11,7,9,18,4,12,1', {'message': 'arrayReverser should return "6,5,101,3,11,7,9,18,4,12,1"'});


// 6.
// Write a function that accepts an array argument
// and returns the sum of all of the numbers in the array
// A:
//array -> number
function sumArrayOfNumbers(arrayOfNumbers){
    var sum = 0;

    for (var i=0; i<arrayOfNumbers.length; i++){
        var currentElement = arrayOfNumbers[i];
        sum += currentElement;
    }

    return sum;

}


console.assert(sumArrayOfNumbers(numbers) === 177, {'message': 'sumArrayOfNumbers should return 177'});


// 7.
// Write a function that accepts an array argument
// and returns an array of only the numbers greater than 10
// A:

//array -> array

function numbersOver10(arrayOfNumbers){
    var numbersOver10Array= [];

    for(var i =0; i< arrayOfNumbers.length; i++){
        var currentElement = arrayOfNumbers[i];
        if(currentElement > 10){
            numbersOver10Array.push(currentElement)
        }
    }
    
    return numbersOver10Array;
}


console.assert(numbersOver10(numbers).toString() === "12,18,11,101", {'message': 'numbersOver10 should return "12,18,11,101"'});


// 8.
// Write a function that accepts both an array and number argument
// and returns an array of only the numbers greater than the number passed to the function
// A:

// array, number -> array
function numbersOverX(arrayOfNumbers, num){
     var numbersOverXArray= [];

    for(var i =0; i< arrayOfNumbers.length; i++){
        var currentElement = arrayOfNumbers[i];
        if(currentElement > num){
            numbersOverXArray.push(currentElement);
        }
    }
    return numbersOverXArray;
}


console.assert(numbersOverX(numbers, 15).toString() === "18,101", {'message': 'numbersOverX should return "18,101"'});

// 9.
// Write a function `joinArrays()` that takes an array of arrays,
// and returns a single array with the contents of the second array
// listed after the contents of the first array
var numbers = [1,12,4,18,9,7,11,3,101,5,6];
var numbersTwo = [33,56,72,2,5,66,90,21,42];
// A:
//array[array array] -> array
function joinArrays(arrayOfArrays){
    var combinedArray = arrayOfArrays[0].concat(arrayOfArrays[1])
    
    return combinedArray;
}


console.assert(joinArrays([numbers, numbersTwo]).toString() === '1,12,4,18,9,7,11,3,101,5,6,33,56,72,2,5,66,90,21,42', {'message': 'joinArrays should return "1,12,4,18,9,7,11,3,101,5,6,33,56,72,2,5,66,90,21,42"'});


// 10.
// Using the `instructors` array, comment the value of each variable below
var instructors = [
    ['JD','JavaScript'],
    ['Tim','JavaScript'],
    ['Brit','Ruby'],
    ['Joe','iOS'],
    ['Dan','JavaScript'],
    ['Will','JavaScript'],
    ['Calvin','JavaScript'],
    ['James','Ruby']
];

var instructorNameDiscipline = instructors[5];
// greenvIlleInstructor = ['Will', 'Javascript']

var instructorOne = instructors[4][0];
// instructorOne = 'Dan'

var instructorTwo = instructors[0][1];
// instructorTwo = 'Javascript'

var instructorThree = instructors[2][0];
// instructorThree = 'Brit'