be

2 . score = document . getelementbyid(" score ")。 Value; The meaning of this sentence. And the meaning of getElementById and value.

Gets the value of the value attribute of the tag with the id attribute score in html.

GetElementById: get the element object by Id.

Value: An attribute of an element object.

3. What is 3.parseInt?

Format data into shapes.

4. What is 4.case?

Switch case statement

The Case in the switch is followed by qualified data.

5.5.does break mean to terminate?

Yes, jump the switch. If you don't write, you will continue to carry out the next case until the end.