JavaScript Quiz

What does document.getElementById("demo") do?

• Changes the class of an element

• Adds a new element

• Selects an element with ID "demo"

• Removes an element

Which method adds a click event listener to a button?

• button.listen("click")

• button.addEvent("click", function)

• button.addEventListener("click", function)

• button.onClick(function)

What will [].forEach() do in JavaScript?

• Modify the array directly

• Create a new array

• Loop through each element

• Remove elements from the array

Which method returns a new array with transformed values?

• filter()

• map()

• forEach()

• reduce()

What is the result of typeof null in JavaScript?

• "null"

• "undefined"

• "object"

• "nulltype"

Which of the following is a correct if statement?

• if x == 5:

• if x = 5

• if (x == 5) {}

• if x = 5 {}

What does filter() return?

• A boolean

• A single value

• A modified original array

• A new array with filtered elements

What does the following code output?[1, 2, 3].map(n => n * 2)

• [1, 2, 3]

• [2, 4, 6]

• [1, 4, 9]

• 6

What is the output of this? [1, 2, 3].filter(n => n > 1)

• [1, 2, 3]

• [2, 3]

• [1]

• [3]

Which is the correct way to change the inner text of an HTML element?

• element.innerHTML = "Text"

• element.textContent("Text")

• element.innerText = "Text"

• element.text = "Text"