arrays

Question 1

includes

Answer 1

let b=[10, 20, 30, 40]

b.includes(10)

=> true

Question 2

map

Answer 2

b.map(one=>one+10)

=> [20, 30, 40, 50]

Question 3

reduce

Answer 3

plus

let b=[10, 20, 30, 40]
b.reduce((one,two)=>one+two,0)
=> 100

let b = [10, 20, 30, 40]
b.reduce((one, two) => one * two, 1)
=> 2400

Question 4

reduce #order

Answer 4

let a = [100, 200, 400, 100, 200];

let b = a.reduce((one, two) => {
if (one[two]) {
one[two] = one[two] + 1;
} else {
one[two] = 1;
}

return one;
}, {});

console.log(b);

=> { ‘100’: 2, ‘200’: 2, ‘400’: 1 }

Question 5

remove duplicates

Answer 5

const one = [2, 1, 3, 5, 3, 2];
let two = […new Set(one)]

two # [ 2, 1, 3, 5 ]

Question 6

sort #ordenar

Answer 6

descendente

const one = [2, 1, 3, 5, 3, 2];

const two = one.sort() THE SAME const two = one.sort((a-b)=>a-b)

const two = one.sort() THE SAME const two = one.sort((a-b)=>a-b)

Question 7

array.findIndex(CALLBACK) // array.find(CALLBACK)
=> 3

array.indexof(2)
=>3

Answer 7

they are the same
both return only a value

Question 8

const a = [2, 1, 3, 5, 3, 2];

const b = a.forEach((one, two, three) => {
console.log(one, “=”, two, “=”, three);
});

Answer 8

2 = 0 = [ 2, 1, 3, 5, 3, 2 ]
1 = 1 = [ 2, 1, 3, 5, 3, 2 ]
3 = 2 = [ 2, 1, 3, 5, 3, 2 ]
5 = 3 = [ 2, 1, 3, 5, 3, 2 ]
3 = 4 = [ 2, 1, 3, 5, 3, 2 ]
2 = 5 = [ 2, 1, 3, 5, 3, 2 ]

Question 9

convert // text => array // split

const a=”sadkljsaldkñjf”

const b= a.split(“”)
console.log(b);

Answer 9

[
‘s’, ‘a’, ‘d’, ‘k’,
‘l’, ‘j’, ‘s’, ‘a’,
‘l’, ‘d’, ‘k’, ‘ñ’,
‘j’, ‘f’
]

Question 10

split // second example

const a=”sadkljsaldkñjf”

Answer 10

=> a
[“sadkljsaldkñjf”]

Question 11

condición ? expresión1 : expresión2

Answer 11

const cnt = original.length > modified.length ? original : modified;

Question 12

reverse // split

Answer 12

const a =[100,200,300]

const b=a.reverse()

=> [ 300, 200, 100 ]

Question 13

join

Answer 13

example1

const a = [“one”,”two”,”three”]
const b = a.join(“-“);
=> one-two-three // string

const a = [“one”,”two”,”three”]
const b = a.join();
=> one,two,three // string

Question 14

match // string.match(regex)

Answer 14

let text = “El gato se sube al árbol.”;

let result = text.match(/gato/);
console.log(result); // Output: [“gato”]

result = text.match(/perro/);
console.log(result); // Output: null