"For" deck

Question 1

for..in used with Objects?

Answer 1

Yes

Question 2

for..in used with Arrays?

Answer 2

Yes, not advised

Question 3

for..in used with Strings

Answer 3

Yes, not advised

Question 4

for..of used with Objects?

Answer 4

No

Question 5

for..of used with Arrays?

Answer 5

Yes

Question 6

for..of used with Strings

Answer 6

Yes

Question 7

const obj = {
	a: 1,
	b: 2,
	c: 3,
	d: 4
}

WRITE A FOR..IN LOOP

// Result: 1, 2, 3, 4

Answer 7

for (var property1 in object1) {
console.log(object1[property1]);
}

Question 8

Write a blank for in loop

Answer 8

for (variable in enumerable) {
	// do stuff
}

Question 9

const array = [‘a’, ‘b’, ‘c’, ‘d’];

Write a for loop

// Result: a, b, c, d

Answer 9

for (let i = 0; i < array.length; i++) {
  console.log(array[i]);
}

Question 10

The for..of loop doesn’t work with Objects because they are not ________ and therefore don’t have a [Symbol.iterator] property.

Answer 10

“iterable”,

Question 11

The for..of loop doesn’t work with_________ because they are not “iterable”, and therefore don’t have a [Symbol.iterator] property.

Answer 11

Objects

Question 12

The for..of loop works well with________ and_________, as they are iterable. This method is a more reliable way of looping through an Array in sequence.

Answer 12

Arrays

Strings

Question 13

it is generally advised that _________not be used with Arrays, particularly because it cannot be guaranteed that the iteration happens in sequence, which is usually important for Arrays

Answer 13

for..in

Question 14

let iterable = [10, 20, 30];

write for..of

// 10
// 20
// 30

Answer 14

for (const value of iterable) {
console.log(value);
}

Question 15

let iterable = ‘boo’;

write for..of

// "b"
// "o"
// "o"

Answer 15

for (let value of iterable) {
console.log(value);
}

Question 16

var string1 = "";
var object1 = {a: 1, b: 2, c: 3};

write a for in

console.log(string1);
// expected output: "123"

Answer 16

for (var property1 in object1) {
string1 += object1[property1];
}

Question 17

__________ should not be used to iterate over an Array where the index order is important.

Answer 17

for…in

Question 18

for…in should not be used to iterate over an_______ where the index order is important.

Answer 18

Array

Question 19

var fruits =[“apple”, “pear”, “plum”];

use for Each to interate in console.

Answer 19

fruits.forEach(fruit => console.log(fruit));

Question 20

the for Each loop cannot _________ of loops like the for loop

Answer 20

break

Question 21

WRITE A REVERSE STRING for string using FOR

function reverseString(str) {

}
reverseString(‘hello’);

Answer 21

var newString = "";
    for (var i = str.length - 1; i >= 0; i--) {
        newString += str[i];
    }
    return newString;

Question 22

const emotions = ['happy', 'sad', 'angry'];
emotions.forEach( emotion => console.log(\_\_\_\_\_\_\_\_\_) );

WHAT GOES IN _______

// Will log the following:
// 'happy'
// 'sad'
// 'angry'

Answer 22

emotion

Question 23

const emotions = ['happy', 'sad', 'angry'];
emotions.forEach( \_\_\_\_\_\_\_\_\_\_\_\_\_\_ );
// Will log the following:
// 'happy'
// 'sad'
// 'angry'

Answer 23

emotion => console.log(emotion)

Question 24

function reverseString(str) {
    var newString = "";
    for (var i = str.length - 1; i >= 0; i--) {
        \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 
    }
    console.log (newString);
}
reverseString('hello');

Answer 24

newString += str[i];

Question 25

``` var arr = [[1,2], [3,4], [5,6]]; WRITE NESTED FOR loop using FOR console.log(arr[i][j]); } } ```

Answer 25

``` for (var i=0; i < arr.length; i++) { for (var j=0; j < arr[i].length; j++) { ```

Question 26

``` var arr = [[1,2], [3,4], [5,6]]; for (var i=0; i < arr.length; i++) { for (var j=0; j < arr[i].length; j++) { _____________ print to console } } 1,2,3,4,5,6 ```

Answer 26

console.log(arr[i][j]);

Question 27

``` var cubes = [ [1, 2, 3], [4, 5, 6], [7, 8, 9], ]; ``` "cube[0][0] = 1" WRITE NESTED FOR LOop

Answer 27

``` for(var i = 0; i < cubes.length; i++) { var cube = cubes[i]; for(var j = 0; j < cube.length; j++) { display("cube[" + i + "][" + j + "] = " + cube[j]); } } ```

Question 28

var arr = [[1,2], [3,4], [5,6]]; //write NESTED for loop i j console.log(arr[i][j]); } }

Answer 28

``` for (var i=0; i < arr.length; i++) { for (var j=0; j < arr[i].length; j++) { ```

Question 29

var arr = [[1,2], [3,4],[5,6]]; write FOR IN

Answer 29

``` for (i in arr){ for (j in arr[i]){ console.log(arr[i][j]); } } ```

Question 30

Using forEach, copy only the first 2 characters of each string in the days array and store the abbreviations in the dayAbbreviations array. ``` const days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']; let dayAbbreviations = []; ```

Answer 30

``` const dayAbbreviations = days.forEach(day.slice(0,2)) dayAbbreviations.push(dayAbbreviations) ```

Question 31

Using forEach, iterate over the numbers array and multiply each number by 10, storing these new numbers in the times10 array. ``` const numbers = [1,2,3,4,5,6,7,8,9,10]; let times10 = []; ``` USE PUSH

Answer 31

numbers.forEach(function(number){ times10.push(number * 10) });

Question 32

MAKE TO ARROW FUNC numbers.forEach(function(number){ times10.push(number * 10) });

Answer 32

numbers.forEach(number => times10.push(number * 10));

Question 33

You should favor _______and .__________ if you prefer the functional paradigm of programming. For other paradigms (and even in some rare cases within the functional paradigm),_________ is the proper choice.

Answer 33

.map() .reduce() .forEach() i

Question 34

ForEach forEach is an Array method that we can use to execute a function on each element in an array. It can only be used on _______ , __________ & ____________

Answer 34

Arrays, Maps, and Sets.

Question 35

WRITE AS A FOREACH ``` const arr = ['cat', 'dog', 'fish']; for (i = 0; i < arr.length; i++) { console.log(arr[i]) } ```

Answer 35

arr.forEach(element => { console.log(element); });

Question 36

``` const obj = { a: 1, b: 2, c: 3, d: 4 } ``` for (let elem in obj) { console.log( obj[elem] ) }

Answer 36

1 , 2, 3, 4

Question 37

``` for (let elem in obj) { console.log(______________); } // a = 1 // b = 2 // c = 3 // d = 4 ```

Answer 37

`${elem} = ${obj[elem]}`

Question 38

``` const arr = ['cat', 'dog', 'fish']; for (let i in arr) { ____________ } // cat // dog // fish ```

Answer 38

console.log(arr[i])

Question 39

const string = 'hello'; //write a FOR...IN ``` // h // e // l // l // o ```

Answer 39

for (let character in string) { console.log(string[character]) }

Question 40

A drawback to using forEach is it cannot use

Answer 40

break

Question 41

``` var sandwiches = [ 'tuna', 'ham', 'turkey', 'pb&j' ]; ``` sandwiches.forEach(function (sandwich, index) { console.log(index); console.log(sandwich); }); // returns

Answer 41

0, "tuna", 1, "ham", 2, "turkey", 3, "pb&j"

Question 42

``` var sandwiches = [ 'tuna', 'ham', 'turkey', 'pb&j' ]; ``` //code using forEach // returns 0, "tuna", 1, "ham", 2, "turkey", 3, "pb&j"

Answer 42

sandwiches.forEach(function (sandwich, index) { console.log(index); console.log(sandwich); });

Question 43

``` arr.forEach(function callback(_______ , _______, ______) { //your iterator } ```

Answer 43

current value, index, array

Question 44

``` var words = ['one', 'two', 'three', 'four']; words.forEach(function(word) { console.log(word); if (word === 'two') { words.shift(); } }); ```

Answer 44

``` // one // two // four ```

Question 45

WRITE AS A FOR const fruits = ['apple', 'pear', 'cherry']; // logs apple, pear, cherry

Answer 45

for (i = 0; i < fruits.length; i++) { console.log(fruits[i]) }

Question 46

WRITE AS A WHILE const fruits = ['apple', 'pear', 'cherry'];

Answer 46

``` var counter = 1; while (counter < 10 ) { console.log( counter ); counter = counter + 1; } ```

Question 47

WRITE AS A DO WHILE const fruits = ['apple', 'pear', 'cherry'];

Answer 47

``` var counter = 1; do { counter = counter + 1; console.log( counter ); } while (counter < 10); ```

Question 48

WRITE AS A MAP const fruits = ['apple', 'pear', 'cherry']; console.log(capitalizedFruits) // [ 'APPLE', 'PEAR', 'CHERRY' ]

Answer 48

const capitalizedFruits = fruits.map( fruit => fruit.toUpperCase() );

Question 49

Nesting _______ is really a bad practice. Instead of that you can use the map() function to get data.

Answer 49

foreach

Question 50

it iterate through a nested array its best to use _____ or ______

Answer 50

for | map

Question 51

``` var array1 = ['a', 'b', 'c']; var iterator = array1.keys(); ``` write a FOR OF loop // expected output: 0 1 2

Answer 51

for (letkey of iterator) { console.log(key); }