//ES6 Array Extensions


//Creates an array of length n but fills it with undefined values
let array = Array(5);
console.log(array);


// array.of() creates array of ... items
let arrayOf = Array.of(5);
let arrayOfTwo = Array.of(5, 111, 52);
console.log(arrayOf);
console.log(arrayOfTwo);


// .from allows us to create a new array based on an old array. also .from allows us to manipulate the old array
// Array.from leaves the origional array unchanged
let arrayFromOld = [32, 33, 11];
console.log(arrayFromOld)

let arrayFromNew = Array.from(arrayFromOld, value => value * 12)
console.log(arrayFromNew)


// .fill takes an origional array, and replaces every value with x
// .fill allows an optional argument
let arrayFill = [1, 2, 3];
let arrayFillArg = [1, 2, 3];

arrayFill.fill(150); // replaces all
arrayFillArg.fill(150, 0, 2); // replaces some with optional argument

console.log(arrayFill);
console.log(arrayFillArg);


// .find returns elements based on meeting a criteria
// expects a function as an argument
// stops after the first match found

let arrayFind = [5, 15, 33];

console.log(arrayFind.find(val => val >= 13)); //Returns : 15


// find an object in an array by one of its properties

const inventory = [
    {name: 'apples', quantity: 2},
    {name: 'bananas', quantity: 0},
    {name: 'cherries', quantity: 5}
];

function isCherries(fruit) { 
    return fruit.name === 'cherries';
}

console.log(inventory.find(isCherries)); 
// { name: 'cherries', quantity: 5 }


let baseArray = [1, 2, 3];
let copyEndArray = [1, 2, 3];

// copyWithin() - allows us to copy a value inside of an array
// expects what to copy, and where to copy it
// **Overwrites** the origional array


//simple copy
console.log(baseArray.copyWithin(1, 2));


//start - end argument copy
console.log(copyEndArray.copyWithin(1, 0, 2));


// array.entries() 
// returns a iterator and description of [index , value] of each of the values within the array


let entriesArray = [1, 2, 3];

let it = entriesArray.entries();

for (let element of it) {
  console.log(element);
}