Blookly trắc nghiệm 10 - Phan Thủy

1. What is the result of the following expression?

• A. true

• B. false

• C. undefined

• D. Error

2. Which of the following syntax is used to copy an object in JavaScript?

• A. let newObj = oldObj.clone();

• B. let newObj = Object.assign({}, oldObj);

• C. let newObj = Object.copy(oldObj);

• D. let newObj = oldObj;

3. In JavaScript, what is the async keyword used for?

• A. Declare an asynchronous function

• B. Pause a synchronous function

• C. Terminate an asynchronous function

• D. Start a new process

4. What is the result of the following expression?

• A. 30

• B. undefined

• C. null

• D. Error

5. What is the correct syntax to use the reduce function to sum elements in an array?

• A. arr.reduce((a, b) => a + b);

• B. arr.reduce((a, b) => a + b, 0);

• C. arr.reduce((total, value) => total + value);

• D. arr.reduce((total, value) => total + value, 0);

6. What is the result of the following expression?

• A. true

• B. false

• C. undefined

• D. null

7. What is the result of the following expression?

• A. true

• B. false

• C. undefined

• D. Error

8. What is the result of the following expression?

• A. true

• B. false

• C. undefined

• D. Error

9. In JavaScript, in what context is the yield keyword used?

• A. In a normal function

• B. In an asynchronous function

• C. In a generator function

• D. In an arrow function

10. What is the result of the following expression?

• A. [1, 2, 3, 4, 5]

• B. [2, 3, 4, 5]

• C. [1]

• D. [2, 3, 4]