Quiz

JavaScript ES6 Quiz

8 questions about the features introduced in JavaScript starting with ES6: let/const, arrow functions, destructuring, and more.

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Question 1 of 8

Which of these was introduced in ES6?

var✓✗ function✓✗ let and const✓✗ if/else✓✗

Question 2 of 8

What does an arrow function that adds two numbers look like?

function(a, b) { return a + b }✓✗ (a, b) => a + b✓✗ a, b => { a + b }✓✗ func (a, b) => a + b✓✗

Question 3 of 8

What does const { name, age } = user; do?

Creates a new object✓✗ Destructuring — pulls the name and age properties out of the user object✓✗ Copies the entire user object✓✗ It's a syntax error✓✗

Question 4 of 8

What is a template literal?

A string in double quotes✓✗ A string in backticks that can embed ${variables}✓✗ An array of strings✓✗ A function for formatting numbers✓✗

Question 5 of 8

What does the spread operator ...arr do?

Removes elements from an array✓✗ Expands the array's elements individually✓✗ Sorts the array✓✗ Creates a deep copy of an object✓✗

Question 6 of 8

How do ES6 modules (import/export) differ from the old approach?

They don't differ at all✓✗ They let you explicitly export and import parts of code between files✓✗ They only work in Node.js✓✗ They aren't supported in browsers at all✓✗

Question 7 of 8

What does function greet(name = "Guest") {} return when called as greet()?

undefined✓✗ "Guest"✓✗ An error✓✗ null✓✗

Question 8 of 8

What is a class in ES6?

A new data type✓✗ Syntax for describing objects and their behavior✓✗ A way to declare variables✓✗ A replacement for arrays✓✗

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