JavaScript Concepts Quiz

What is the correct way to declare a variable in JavaScript?

• `var myVariable;`

• `variable myVariable;`

• `v myVariable;`

• `declare myVariable;`

Which of the following is a correct way to define a function in JavaScript?

• `function myFunction() {}`

• `def myFunction() {}`

• `function: myFunction() {}`

• `func myFunction() {}`

What is the purpose of the `async` keyword in JavaScript?

• To make a function run faster

• To declare a function that returns a promise

• To pause the execution of a function

• To make a function synchronous

Which method is used to select an element by its ID in the DOM?

• `document.getElementById()`

• `document.querySelector()`

• `document.getElementsByClassName()`

• `document.getElementsByTagName()`

What does the `map()` method do in JavaScript arrays?

• It modifies the original array

• It creates a new array with the results of calling a provided function on every element

• It filters the array based on a condition

• It sorts the array in ascending order

How can you create a promise in JavaScript?

• `let promise = new Promise();`

• `let promise = Promise.create();`

• `let promise = new Promise((resolve, reject) => {});`

• `let promise = Promise();`

Which of the following is a valid way to add an event listener to a DOM element?

• `element.addEventListener('click', function() {});`

• `element.on('click', function() {});`

• `element.listen('click', function() {});`

• `element.event('click', function() {});`

What is the output of the following code snippet? ```javascript let x = 10; function test() { let x = 20; console.log(x); } test(); ```

• `10`

• `20`

• `undefined`

• `ReferenceError`

Which array method would you use to remove the last element from an array?

• `array.pop()`

• `array.push()`

• `array.shift()`

• `array.unshift()`

What is the purpose of the `await` keyword in JavaScript?

• To pause the execution of a function until a promise is resolved

• To make a function asynchronous

• To handle errors in promises

• To create a new promise