JavaScript DOM Manipulation Quiz

What does the following JavaScript code do?

const element = document.getElementById("intro");

• Selects the first

  element in the document

• Selects the element with the id "intro"

• Selects all elements with the class "intro"

• Selects all

  elements inside the element with id "intro"

What happens if the specified ID does not exist? const element = document.getElementById("missingID");

• Returns null

• Returns an empty string

• Throws an error

• Returns an empty object

Which JavaScript method retrieves all paragraph

elements in the document?

• document.getElementById("p")

• document.getElementsByClassName("p")

• document.getElementsByTagName("p")

• document.querySelectorAll("#p")

What will the following code return?

const x = document.getElementsByClassName("intro");

• The first element with class "intro"

• A collection of all elements with class "intro"

• An array of all elements with class "intro"

• The last element with class "intro"

Which method selects all paragraph

elements with class "intro"?

• document.querySelector("p.intro")

• document.getElementsByClassName("intro")

• document.querySelectorAll("p.intro")

• document.getElementsByTagName("p.intro")

What does the following code do?

const x = document.getElementById("main");

const y = x.getElementsByTagName("p");

• Selects all paragraph

  elements inside the element with id "main"

• Selects all paragraph

  elements in the document

• Selects the first paragraph

  inside "main"

• Throws an error

Which JavaScript code retrieves a form with the name "frm1"?

• document.getElementById("frm1")

• document.getElementsByTagName("form")

• document.forms["frm1"]

• document.querySelector("#frm1")

What does the following code do?

const x = document.forms["frm1"];

let text = x.elements[0].value;

• Retrieves the value of the first element in form "frm1"

• Retrieves the form's name

• Retrieves the number of elements in "frm1"

• Retrieves the type of the first element

Which condition correctly checks if an input field is empty?

• if (x === null)

• if (x == "")

• if (x.length > 0)

• if (x !== undefined)

What does the return false; statement in the validateForm function do?

function validateForm() {

let x = document.forms["myForm"]["fname"].value;

if (x == "") {

alert("Name must be filled out");

return false; }

}

• Submits the form

• Stops the form from being submitted

• Clears the form fields

• Refreshes the page