break-continue-and-string-and-array-methods.js

// Break =================================
// Break ends a loop immediately

console.log('=== BREAK ===');

for (let i = 0; i < 10; i++) {
    console.log(i);
    if (i === 5) {
        break;
    }
}

console.log('done');

// Continue =================================
// Skips an iteration of the loop

console.log('=== CONTINUE ===');

for (let i = 0; i < 10; i++) {
    if (i === 3) {
        continue;
    }
    console.log(i);
}

// Switch, case statement =================================

const name = 'Lee';

if (name === 'Lee') {
    // DO something
} else if (name === 'Mesi') {
    // Do something else
} else if (name === 'Andy') {
    // Etc
} else {
    // If none of the conditions are true
}

// Switch case statement is identical to a bunch of if else statements

switch (name) {

    case 'Lee':
        // Do something
        break;
    
    case 'Mesi':
        // Do something
        break;

    case 'Andy':
        // Etc
        break;

    default:
        // If none of the conditions are true
        break;
}

// .split, .join =================================

// Input: 'a bunch of words'
// 1. str.split(' ')
//     => ['a', 'bunch', 'of', 'words']
// 2. TODO: loop through each, capitalize first letter
//    => ['A', 'Bunch', 'Of', 'Words']
// 3. arr.join(' ');
// Output: 'A Bunch Of Words'

// Commaify, replaces spaces with commas
// Input: 'a bunch of words'
// Output: 'a,bunch,of,words'
function commaify(str) {
    const arrOfWords = str.split(' ');
    return arrOfWords.join(',');
}

console.log(commaify('a bunch of words'));

// How does split work?

// str.split(' ')
// 'a bunch of words'
// => ['a', 'bunch', 'of', 'words']

// How does join work?

// arr.join('')
// ['a', 'bunch', 'of', 'words']
// => 'a bunch of words'


// .reduce, .map, .filter =================================

// Reduce =================================
// Take in an array of values, create a new value based on those values

// Sum an arary of numbers
// Input: [1, 2, 3]
// Ouput: 6
function sum(arrayOfNumbers) {
    let output = 0;
    for (const num of arrayOfNumbers) {
        output += num;
    }
    return output;
}

const arrowFunction = () => {

};

function functionDelcaration() {

}

function sum2(arrayOfNumbers) {
    const sum = arrayOfNumbers.reduce(
        (sum, num) => sum + num,
        0
    );
    return sum;
}

// Map =================================
// Takes in array, maps each value to another value (output is array)

// Doubles each number in an array
// Input: [1, 2, 3]
// Output: [2, 4, 6]
function arrayDoubler(numArray) {
    let output = [];
    for (const num of numArray) {
        output.push(num * 2);
    }
    return output;
}

function arrayDoubler2(numArray) {
    const output = numArray.map(
        (num) => num * 2
    );
    return output;
}

// Filter =================================
// Take in an array, return an array with some values filtered out

// Filters out all values greater than 5
// Input: [3, 6, 10]
// Ouput: [3]
function lessThan5(arr) {
    let output = [];
    for (const num of arr) {
        if (num < 5) {
            output.push(num);
        }
    }
    return output;
}

function lessThan5Two(arr) {
    const output = arr.filter(
        (num) => num < 5
    );
    return output;
}