Now we’re getting to It

Question 1

JS: (expression) === VAR ? true: false;

Answer 1

Ternary operator evaluating for a Boolean response

Question 2

JS: (expression) === VAR ? true :
(expression) ? true : false;

Answer 2

Nested ternary: basically if, else if, else
If the first returns false it moves into second line

Question 3

JS: for (const VAR of ARRAY/STR) {
do something;
}

Answer 3

Basic for … of loop. Ideal to iterate thru arrays and strings

Question 4

JS: const { key } = object;
console.log(key);
// prints ‘value’

Answer 4

A destructured assignment
Instead of
const key = object.key;

Question 5

JS: const {key} = object;

key.nestedProperty;
or
key.nestedMethod();

Answer 5

More destructured assignment to access a nested property

Question 6

.forEach() array iterates over array to return on each element but does not return a new array

Answer 6

JS: array.forEach(item => do something);

Question 7

.map()
return a new array with the results of calling a provided function on every element of original array

Answer 7

const newArray = array.map(item =>
do_something);

Question 8

.findIndex() to find the index of an element that matches given criteria

Answer 8

array.findIndex(i => i === 5);

Question 9

JS: array.some()

Answer 9

Interator method that will check if there are ‘some’ given is criteria and return Boolean

Question 10

.filter() to return a new array only with elements that pass a test

Answer 10

arr.filter(i => i != 5);
Returns array where i does not equal 5

Question 11

.reduce() an array to a single value

Answer 11

array.reduce((accumulator, current) => {
return accumulator + current;
})

Question 12

Short circuit evaluation (of an single if/else)
Eg.
if ‘thisVar’ exists use it,
else default to ‘that string

Answer 12

let variable = thisVar || ‘that string’;
Do something;

Question 13

While Loop: continues while condition is true.

Answer 13

let i = 0;
while (i < 5) {
do_something;
i++
}

Question 14

For loop. Runs a specified number of times.

Answer 14

for (let i = 0; i < 5; i ++) {
do _something;
}

Question 15

For loop to iterate array

Answer 15

for (let i = 0; i < array.length; i ++) {
do_something _to _array;
}

Question 16

Do While loop (guarantees at least one iteration over a While loop)

Answer 16

let i = 0

do {
do_something;
i++;
} while ( i < 5)