Review

Question 1

Entering about:blank in the address bar of your browser will:

Accepted Answer

generate and load a minimal blank HTML page into the current tab.

Answer

open a tab with information about your browser.

Answer

clear all inputs on the current page.

Answer

generate a page with information about the browser’s status.

Question 2

Analyze the following code:

let id = "100";
{
let id = 200;
id = id + 1;
console.log(id);
}

Accepted Answer

201

Answer

1001

Answer

101

Answer

200

Question 3

Select a set of data types, containing only complex types:

Accepted Answer

Array, Object

Answer

Object, String

Answer

Boolean, Number, Bigint

Answer

Array, Object, String

Question 4

We can replace the declaration let x = 3e-3; with:

Accepted Answer

let x = 0.003;

Answer

let x = 3000;

Answer

let x = 0.0003;

Answer

let x = 0.333;

Question 5

Using the string interpolation technique, we can create the string:
"I do not like travelling by plane"

Accepted Answer

let means = "plane";
let msg = `I do not like travelling by ${means}`;

Answer

let means = "plane";
let msg = 'I do not like travelling by \{ means \}';

Answer

let means = "plane";
let msg = "I do not like travelling by ${ means }";

Answer

let means = "plane";
let msg = `I do not like travelling by {means}`;

Question 6

We declare a movie object, with two fields: title and year:

let movie = {
title: "Life",
year: 1999

To change the value of the title field to "Matrix" we need to perform:

Accepted Answer

movie.title = "Matrix";

Answer

movie[title] = "Matrix";

Answer

movie{title} = "Matrix";

Answer

title->movie = "Matrix";

Question 7

You declare the following array of animals: let animals = ["canary", "dog", "cat"];. Then, you call the method animals.push("hamster");. What will the animals array look like after calling the method?

Accepted Answer

["canary", "dog", "cat", "hamster"]

Answer

["hamster"]

Answer

["hamster", "canary", "dog", "cat"]

Answer

["canary", "dog", "cat"]

Question 8

A JavaScript code includes the console.log("http://somethingNew.org"); command. Its execution will:

Accepted Answer

display the following message on the console: "http://somethingNew.org".

Answer

display on the console information about the progress of the http://somethingNew.org page loading.

Answer

cause the page http://somethingNew.org to be loaded into the browser.

Answer

send a log with information about the currently executed script to the indicated address http://somethingNew.org.

Question 9

Analyze the code snippet:
let winter = ["December", "January", "February"]; let index = winter.indexOf("February");

What value will the index variable have?

Accepted Answer

2

Answer

"February"

Answer

3

Answer

1

Question 10

In the daysOfWeek variable, you place an array with the names of the days of the week. Which method will you call to reverse the order of the array elements.

Accepted Answer

daysOfWeek.reverse();

Answer

daysOfWeek.invert();

Answer

daysOfWeek = reverse(daysOfWeek);

Answer

daysOfWeek.order(-1);

Question 11

Review the following code:

let msg1 = 'hello';
let msg2 = msg1.slice(-1);
console.log(msg2 ? msg2 : msg2 + msg1);

What will appear on the console as a result?

Accepted Answer

o

Answer

ohello

Answer

hello

Answer

h

Question 12

Analyze the following code:

let test = prompt("Run", "code");

What value will the test variable have if, after running the code, we immediately press the OK button on the newly created dialog?

Accepted Answer

code

Answer

true

Answer

OK

Answer

Run

Question 13

Analyze the following code:

let x = false || true;
let y = "true" && "false";
let z = false && true;
console.log(`${x} ${y} ${z}`);

What will appear in the console as a result of its execution?

Accepted Answer

true false false

Answer

false true true

Answer

false false false

Answer

false false true

Question 14

Analyze the following code:

let a = true && 20;
let b = 0 || 20
let c = 0 && 20;
console.log(`${a} ${b} ${c}`);

What will appear in the console as a result of its execution?

Accepted Answer

20 20 0

Answer

true 20 0

Answer

1 1 0

Answer

true true false

Question 15

Examine the following code:

let a = 20 + "10";
let b = 20 + +"10";
let c = 20 + -"10" + "10";
let d = "10" - "10" + "100";
let e = "A" - "B" + 0xA;
console.log(`${a}, ${b}, ${c}, ${d}, ${e}`);

What will appear on the console as a result?

Accepted Answer

2010, 30, 1010, 0100, NaN

Answer

30, 30, 20, 100, 2

Answer

30, 31, 39, 100, NaN

Answer

2010, 2010, 20-1010, 0100, NaN

Question 16

Which of the following loop instructions checks the loop continuation condition only after the iteration has been completed?

Accepted Answer

do ... while

Answer

for ... in

Answer

while

Answer

for

Question 17

The following function using a function expression has been defined:

let sum = function (a, b) {
    return (a + b);
}

What could the definition of the corresponding arrow function look like?

Accepted Answer

let sum = (a, b) => a + b;

Answer

let sum = function (a, b) => {
 return (a + b); }

Answer

let sum = (a, b) => { a + b; };

Answer

let sum = (a, b)-- > a + b;

Question 18

The temp array contains air temperature data measured over a period of time. You want to display the minimal temperature using the following code:

temp.forEach(e => min = min > e ? e : min);
console.log(min);

What should the declaration of the min variable look like?

Accepted Answer

let min = temp[0];

Answer

let min;

Answer

It’s not necessary, as it will be declared automatically on first use.

Answer

let min = 0;

Question 19

Examine the following code:

let x = [10, 20, 30, 40];
let y = [50, 60];
x.reverse().push(y);
console.log(x.length);

What will appear on the console as a result?

Accepted Answer

5

Answer

6

Answer

4

Answer

2

Question 20

Analyze the following code:

for(let a=1; a<10; a+=2) {
    console.log(a);
};

Which statement can replace the for from the example?

Accepted Answer

let counter = 0;
while (counter++ < 10) console.log(counter++);

Answer

let counter = 1;
while (counter++ < 10) console.log(counter++);

Answer

let counter = 0;
while (counter < 9) console.log(counter++);

Answer

let counter = 0;
while (counter < 10) console.log(counter++);

Question 21

Analyze the following code:

let colors = ['red', 'green', 'blue'];
for (let c of colors) console.log(c);

What will appear on the console as a result?

Accepted Answer

red
green
blue

Answer

['red', 'green', 'blue']

Answer

0
1
2

Answer

3

Question 22

Analyze the following code:

let route = {distance: 131, elevation: 1.4};
for (let k in route) console.log(k);

What will appear on the console as a result?

Accepted Answer

distance
elevation

Answer

131
1.4

Answer

distance

Answer

2

Question 23

Examine the following code:

let a = (n) => {
    return n > 2 ? n * a(n - 1) : 2
}
console.log(a(6));

What will appear on the console as a result?

Accepted Answer

720

Answer

120

Answer

6

Answer

4

Question 24

Examine the following code:

let x = mult(2)(10);
console.log(x); // -> 20

What should the mult function declaration look like if the execution of this code results in a value of 20 in the console?

Accepted Answer

let mult = function (a) {
 return function (b) {
 return a * b;
 }
}

Answer

There is an error in the code and it is not possible to declare such a function correctly.

Answer

let mult = function (a, b) {
 return a * b;
}

Answer

let mult = function (a, b) {
 return b ? mult(b) : mult(a);
}

Question 25

Analyze the code snippet:

let counter = 0;
let userName = "John";

After declaring the counter variable, we want to add a short comment with information about what the variable is used for. To do this, we modify the line with the declaration to the form:

Accepted Answer

let counter = 0; // user visit counter

Answer

// let counter = 0; user visit counter

Answer

let counter = 0; ;;user visit counter

Answer

let counter = 0; /* user visit counter

Question 26

Examine the following code:

x = [40, 10, 30, 20, 50];
x.sort(cmp);

How should the function cmp be declared if, after the code execution, the elements of the array x are sorted in ascending order?

Accepted Answer

let cmp = (a, b) => a - b;

Answer

let cmp = (a, b) => b < a;

Answer

let cmp = (a, b) => b > a;

Answer

let cmp = (a, b) => b - a;

Question 27

Analyze the following code, which is missing one line:

let counter = 2;
let interval = setInterval(() => {
    console.log(counter);
// Insert missing line here.
}, 1000);

What should the missing line look like if the execution of this code results in the console displaying the values 2, 1, and 0 in sequence?

Accepted Answer

if (counter-- <= 0) clearInterval(interval);

Answer

if (counter-- >= 0) clearInterval(interval);

Answer

while (counter-- >= 0) clearInterval(interval);

Answer

clearInterval(interval);

Question 28

Analyze the following code:

function execute(todo, a, b) {
return todo(a, b);
}
console.log(execute(power, 3, 2));

Before declaring the function, we should add one more line of code. Which one, if the execution of the completed code will result in the console displaying the value 9?

Accepted Answer

let power = (x, y) => x ** y;

Answer

let power = () => a ** b;

Answer

let power = 9;

Answer

let power = (x,y) => x * y;

Question 29

Analyze the following code:

const a = "hello";
    console.log(a.toUpperCase());
}
} catch (error) {
    console.log(a)
} finally {
    console.log(a);
}

What will happen as a result of its execution?

Accepted Answer

The following words will appear in the console on subsequent lines: HELLO and hello.

Answer

The following words will appear in the console on subsequent lines: HELLO, hello, and hello.

Answer

The following words will appear in the console on subsequent lines: hello and hello.

Answer

The following word will appear in the console: HELLO.

Question 30

Placing a debugger; statement in the program code will:

Accepted Answer

pause the program with the ability to continue, as long as the execution environment supports “debugging functionality”.

Answer

stop the program without the ability to continue, as long as the execution environment supports “debugging functionality”.

Answer

put the interpreter into report mode, which will cause the console to print out all sequentially executed commands.

Answer

cause the console to display the completion status of the statement preceding the debugger.

Review

Crea una cuenta gratis para terminar este test

Preguntas del test (30)

Información

Escríbenos

¿Qué te parece el nuevo diseño?