array-tips.js

/**
 * -------------------------------------------------------------
 * 1. Removing Duplicates from an array
 * -------------------------------------------------------------
 * @description We make use of sets and create an array from a Set. Sets don't allow duplicates
 * @returns [1,2,3,1,2,3] -> [1,2,3]
 */

const duplicates = [1, 2, 3, 1, 2, 3];
const removedDuplicates = Array.from(new Set(duplicates));
const removedDuplicatesSpread = [...new Set(duplicates)];

/**
 * -------------------------------------------------------------
 * 2. Empty an array
 * -------------------------------------------------------------
 * @description Set length of array = 0
 * @returns ["a","b","c"] -> []
 */

const arrayToEmpty = ["a", "b", "c"];
arrayToEmpty.length = 0;

/**
 * -------------------------------------------------------------
 * 3. Map an array without using array.map
 * -------------------------------------------------------------
 * @description We can use Array.from() to accomplish this
 * @returns [1,2,3,4,5] -> [2,4,6,8,10]
 * @returns ['John Doe', 'Karen Smith', 'Joey Brown']
 */

const nums = [1, 2, 3, 4, 5];
const mappedArray = Array.from(nums, num => num * 2);

const people = [
    {
        firstName: "John",
        lastName: "Doe"
    },
    {
        firstName: "Karen",
        lastName: "Smith"
    },
    {
        firstName: "Joey",
        lastName: "Brown"
    }
];

const names = Array.from(people, person => `${person.firstName} ${person.lastName}`);

/**
 * -------------------------------------------------------------
 * 4. Reversing an array
 * -------------------------------------------------------------
 * @description Built in method using .reverse()
 * @returns [4,3,2,1] -> [1,2,3,4]
 */

const arrayToReverse = [4, 3, 2, 1];
console.log(arrayToReverse.reverse());

/**
 * -------------------------------------------------------------
 * 5. Filling an array with .fill() and .map() 
 * -------------------------------------------------------------
 * @description We can use Array.fill() and then .map()
 * @returns array of 10 random different numbers 
 */

// This has no random instance or difference
const randomNumbers = new Array(10).fill(getRandomNumberBetween(10));
console.log(randomNumbers);

const randomNumbers2 = new Array(10).fill().map(_ => getRandomNumberBetween(10));
console.log(randomNumbers2);

// Get random number between function
function getRandomNumberBetween(num) {
    return Math.floor(Math.random() * num + 1);  
}