The code in this section mainly uses the onMousedown event and the event.button attribute. The main functions and usage are as follows.
• The setTimeout method, when executed, executes the expression once and only once after delaying the specified time after loading.
• The charAt method returns a character value that is located at the specified index position. The first character in the string has index 0, the second has index 1, and so on. Index values outside the valid range return an empty string.