Câu 2: 70-480: MCSD Programming in HTML5 with JavaScript and CSS3

You develop an HTML5 webpage. You have the following HTML markup: You need to prevent users from entering specific characters into the username field. What should you do?

1. A. Using the keyup event, add an anonymous function that returns true when a specific character keycode value is determined.
2. B. Using the change event, add an anonymous function that returns true when a specific character keycode value is determined. — đáp án hiện tại
3. C. Using the keydown event, add an anonymous function that returns false when a specific character keycode value is determined.
4. D. Using the change event, add an anonymous function that returns false when a specific character keycode value is determined.