HTML and CSS Reference
4. Save your changes to the file, and then reload hanjie.htm in your Web browser.
5. Click different data cells within the Web table and verify that when you repeatedly
click a cell, the background color changes from gold to gray to white and back to
gold again (see Figure 13-20).
Partially solved puzzle
Applying a Timed Command to a Style
Hanjie puzzles can be extremely difficult; one early mistake can result in dozens of mis-
takes later on. Rebecca wants to give frustrated users the ability to peek at the solution by
clicking the Peek button on the Web page, causing the browser to highlight any incor-
rectly darkened cells in red and highlight any cells incorrectly marked as empty in pink.
The drawGrid() function that generates the HTML code for the hanjie puzzle Web
table adds class attributes to all of the table data cells, placing those cells in either the
marked class or the empty class. You'll start creating the peek() function now by generat-
ing collections of marked and empty cells using the querySelectorAll() method.