DOM Manipulation

Question 1

Why is storing information about a program in variables better than only storing it in the DOM?

Answer 1

It is easier to access variables. If information was only stored in the DOM, you’d have to query the DOM every time you want to access the information.

Question 2

Is the event parameter of an event listener callback always useful?

Answer 2

Not always.

Question 3

What is the className property of element objects?

Answer 3

It is a string containing the value of the class attribute on that element.

Question 4

How do you update the CSS class attribute of an element using JavaScript?

Answer 4

By using the className property to change or retrieve the class applied on the element.

Question 5

What is the textContent property of element objects?

Answer 5

It is the text content of the element and any child element as a string.

Question 6

How do you update the text within an element using JavaScript?

Answer 6

By using the textContent property. Text can be updated by assigning it a new value.

Question 7

Would this assignment be simpler or more complicated if we didn’t use a variable to keep track of the number of clicks?

Answer 7

More complicated.